Let me put it this way. I've never seen a company complain about listing stuff on steam and how it killed them or a product. And I've seen a TON of stories (especially indies) where steam vastly increased their total sales and income. Some indies have even talked about how they released on XBLA and PC, and were surprised at how they got far more sales on PC/steam than they got on xbox. I've seen multiple small studios and indies talk about how it literally saved them from closing down by putting products on steam.
Here's an example of what happens when you put a game on steam and discount it:
geekwire.com/2011/experiments-video-game-economics-valves-gabe-newell/
We do a 75 percent price reduction, our Counter-Strike experience tells us that our gross revenue would remain constant. Instead what we saw was our gross revenue increased by a factor of 40. Not 40 percent, but a factor of 40.
When you do a 75% off sale, that means you need 4 times as many sales to stay at same revenue as leaving it at full price. Instead, valve see's titles pick up 40 TIMES the sales.
If they put a GotY edition of DW on steam and list it at $50, and say put a 10% pre-order discount (so its at $45) I can almost guarantee you they would get far more than twice the sales they get now at the $100 price.
BTW, steam takes roughly 30%, that wouldn't require 6 or 7 times the sales. And steam covers the bandwidth and the transaction processing costs, and updating costs, and costs of making sure people who paid for it can play it, etc. So while on the surface it might appear they'd need 1/3rd more sales to make that up, its actually much less.
Here's another example, this time from an indie, the devs of Torchlight:
indiegames.com/2012/07/steam_sales_how_deep_discounts.html
Runic Games CEO Max Schaefer, for instance, tells us that while it's been almost three years since his studio launched Torchlight, Valve's Steam promotions have helped the game maintain healthy sales to this very day.
"We find that we get several thousand percent increases in units and revenue on the days of the Steam sales, and unit sales are usually about double the normal for a few weeks after the sales are over," he says.
THOUSANDS of percent increased sales during a discount. And many more normal full priced sales even after discounts end.
More quotes from that same article
Super Meat Boy co-creator Edmund McMillen, these promotions can increase sales to an almost staggering extent. His 2D dungeon crawler The Binding of Isaac, for example, saw sales multiply by five when it was marked down by 50 percent, and once it hit the front page as a temporary "Flash Deal" (for 75 percent off), sales multiplied by sixty.
Believe it or not, those figures aren't all that unusual. Valve's director of business development, Jason Holtman, says plenty of developers have seen their sales increase exponentially, giving them a very healthy boost in revenue.
"It's not uncommon for our partners to see [a] 10-20 times revenue increase on games they run as a 'Daily Deal.' Some titles really take off and see as much [as a] 70-80 times increase in revenue," Holtman said.
6000% increased sales on a 75% discount (remember you only need 4 times increased sales to maintain revenue) for some nearly unknown indie game called binding of isaac.
And about the sales devaluing games:
the developers we spoke to don't think these promotions are devaluing games at all. Based on the data they've seen, Steam sales have only been a good thing for their business.
Sure, players will jump on the chance to buy a game for $2.50, but the developers have found that Steam consumers are still perfectly willing to pay full price for a game once the sales are over. The "race to the bottom" we've seen on the mobile markets just doesn't seem to be there on Valve's platform.
And one final quote. A few years back valve released what sales did on average during a holiday sale period during 2008 (numbers have vastly improved since then, in part because of steam's enormous growth):
shacknews.com/article/57308/valve-left-4-dead-half
10% sale = 35% increase in sales (real dollars, not units shipped)
25% sale = 245% increase in sales
50% sale = 320% increase in sales
75% sale = 1470% increase in sales