I don't understand this, xbox has pretty similar layout in terms of welcome page, ads, promotions and such. First time I saw the welcome menu of a 360 I was at my buddy's place and I freaked out at how cumbersome everything was. And you say that steam is a PITA? That's some backwards jazz right there.
Not really. I turn the xbox on, get the xbox logo then the game loads. Yes there is a bunch of crude on there now that is unnecessary (the last dashboard update is horrible too) but I'm not forced to have to click through it to play a game. In fact you can use the xbox without ever having to look at any of that at all.
Its probably unjustified to be fair but I have just never liked steam. When I buy a game I don't like having to "register" it so I can play it. CD-keys annoy me enough but having to actually have an account set up, have an internet connection (I know who doesn't have one anyway), log in, register the game, etc, etc. There have been a few games I would have liked to get the PC version of (LFD, MW2, FO3, etc) but I just really don't like that I have to use steam.
Like I said its probably unjustified and steam does have a lot of good points too