I don't see why they would. Steamworks itself is the sales pitch. Firaxis/2k get features like friends lists, achievements, the Steam Cloud save game feature (which is really cool), MP lobbies, and the necessary infrastructure to support it all for $0. You're seeing so many Steamworks games this year because that is a really good deal. Steam also acts as DRM but doesn't carry the same baggage that solutions like SecuROM or Ubisoft do (while some people dislike it, Steam has broad market acceptance).

Valve gets more users on Steam, which they're quite open and upfront about being a motivator.

It's entirely possible that 2k got a better sales deal then normal to be listed on Steam given how high profile Civ 5 is, but the idea that Valve is paying them to carry it is pretty out there. There's nothing nefarious going on here; Steamworks is simply the best solution on the market for what it does.

It's up to the developer to do it. D2D can't legally change Civ 5 and release it without 2k's approval. In this case they'd need to either rip out the features Steamworks is providing (achievements, Steam Cloud saves, the friends list stuff), and either turn all that off or put something else in to do the same thing.

Why would they do this?  Simple.  They are going to sell less copies of Civ V with Steam than if they offered both Steam and non-Steam versions.  How many less, no one knows, but it's non-zero.

Why would any company decide to limit their sales if they're not getting something in return?  This isn't nefarious, it's just business.  Now it's possible that they think the hit will be so small that it's not worth the time and testing to implement a different form of DRM.  That's the case for a lot of Indie titles.  But I don't think that's true in this case.  Civ V is an ultra high profile title that will sell a huge number of copies.  A 1-2% loss of sales could be millions of dollars.

I think it'd be up to the publisher (2k) not the developer (Firaxis).  Decision wise.... removing the steamworks stuff might not pose much of a problem,  particularly if Stardock::Reactor can replace it.  I think it would be the DRM method that holds things up.  I get the feeling that 2k may not easilly release thier grip.  And I imagine they very much want all that user data which steam provides.  If I had to guess, I'd say that 2k would rather choke the life out of something than to loosen their grip.

EDIT:  I see this point frequently missed....

A motivating factor for publishers to choose steam, is that steam provides them with undisclosed user data.  They don't tell us exactly what info is mined from our machines.  Marketers have a great fondness for user data.  The pimping of my user data is yet another reason I dislike steams methods.

Another misc point...  requiring the install (and preventing the uninstall) of the steam store does NOT gain Civ5 more exposure (new players, more sales).  The game would be available on steam regardless.  But it does gain steam more users.  It forces ALL Civ5 players to have the steam store active on thier machines.  If you uninstall the steam store, you cannot play Civ5.  Impulse does not work in this way. 

Go back and read what I actually said. I never said that Steam isn't a digital distribution service. I said I was talking about the use of steam as a copyright method for games. This is a completely seperate issue.

Then there's two possibilities:

1. They think that the lost sales number will be more like 0.01%, which given the cost of integrating and testing a replacement probably wasn't worth worrying about, especially since there wasn't anything during development that did everything Steamworks does. (Reactor is very new, but Stardock could always go pitch it to them.) Given that outside of forums like these you find just as many people saying "I only buy games on Steam" as you do people who say "I refuse to buy games on Steam", I really doubt the lost sales are that big a number for a game this big.

2. Valve gave them a better publishing deal then usual, something like 25% instead of the standard 30%. If that's the case, 2k makes more money off every copy sold on Steam and the extra money will easily make up for any lost sales.

Since anybody selling a really big game has the market clout to try and negotiate with Valve on Steam's cut, there's really nothing out of the ordinary going on.

Again this is an issue with digital downloads in general. It does mean that your potentially at risk if you buy a game online from Steam or Impulse or any other service (personally I choose to take the risk but that's my choice). But it has nothing to do with the use of Steam as a copywrite method for games you own physical copies of which is what you were complainign about originally.

One competitor cant just arrange a deal that keeps the others from selling the same product. It's not a publisher&developer&valve deal, it's just competition.  This is starting to look like M$ with their saying what goes pre-installed on every copy of Windows. 

Physical or digital copy makes no difference.

If you uninstall steam you can't play Civ5.  If you uninstall Impulse you can still play Elemental.

It matters not what happens with Impulse.  Players can still play their games even if Impulse goes defunct.  With Civ5, players must run steam and do a "systems check".  If all systems are go, then the player can play the game.  steam can prevent access to your games.  Do you see the difference??  

Just me reading the supposed, "OMG Steam only release article" But no where does it say that CIV V will be available only via Steam. It says that the pre-order versions can be downloaded early via steam, and that copies purchased via Steam will have a new civ and map included in the game (which considering how much you can mod a civ game is nothing).

Oh, steamworks will be included in the game. Whoppity-do. It won't cause the game to not load, just means any achievements or internet multilayer is out for me. Good thing LAN connections were confirmed still.

So all in all, the article is no different then saying Wal-Mart editions have a new shiny toy gun or some such, and in addioton to all the old multiplayer functions we gave you in Civ IV you now get a matching style via steam if you want it.

Wow. End of the world type stuff.

Uh, it's all over the web, including official sources from 2K games.  Civ V REQUIRES Steam.  End of story.

Don't let the facts get in the way of your attitude, though.

1.  Uh...  what?   People saying that they only buy on Steam were fine regardless.  No one is discussing the idea that Civ V shouldn't be offered on Steam at all. 

Anyway, the number of lost sales is probably in the high thousands, low tens of thousands.  That's real money.

2.  However, the question is, did Valve give them a better deal because it's exclusive?  They almost certainly did.  This is, de facto, more money in 2K's pocket, and is the same as Valve paying 2K to make it exclusive.

Again, I'm not saying that this is out of the ordinary, I don't know why you persist in trying to cast my comments in that light.  This is just ordinary business.  The business of screwing the consumer

1. how did you get to that number?

2. unless you are blind you can see Civ5 on D2D so its clear that Civ5 isnt Steam exclusive.

D2D gives you a Steam activation code. Civ 5 is indeed Steam exclusive.

The primary reason behind 2K's decision to use Steamworks:

Piracy.

All other features are secondary to Steam's ability to reduce piracy. Steam is the most beloved DRM system on the market. Its fans zealously defend it, the press adores it, and while publishers would prefer to keep more control over their products, Steam is a potent DRM system that doesn't generate negative press, publishers welcome it. Other than the forfeiture of some control, publishers love Steamworks because they are able to fight piracy without sacrificing image.

Until Stardock's Impulse::Reactor matures and can effectively compete with Steamworks, expect an increasing number of Steam-mandatory titles (they will be sold in retail stores or on D2D, but Steam will be required for both installation and use of the software). Without worthy competition, the end result is a console-like level of single-party control, in which one company will have disproportionate power in determining software distribution policy.

But hey, Valve can do no wrong, so this is all for the better.