Steam is PC only. PC games have no royalty fees, which results in a much lower cost. All console games have to pay royalty fees to get their game on a particular console....which drives up the cost.
So the comparison is flawed.
It's still a platform to buy games and it's an option if you happen to have a 360 and PC. Even if we exclude all other PC benefits, buying the new DmC for $37.50 on PC instead of $60 for the 360 is an option I'd rather take. Royalty fees don't account for how Microsoft completely overcharges for some games.
Well I kinda prefer digital because you only buy it once and don't need to buy it again (DVDs will stop working for some time), besides loading times are much better.
But yeah, having a physical copy means you actually OWN the game, but I'm afraid some generations later, that console won't play my physical copy (for example: Wii U and its lack of GameCube compatibility).
I think I would rather have it physical, and if it stops working, go digital. :)