WTF am I reading about paying for multiplayer with GFWL? I never paid a cent. But whatever. GFWL failed because Microsoft focused on Xbox and left GFWL to rot, plain and simple. Not a thing wrong with Steam. I can't find much wrong with Origin, either, except that they don't have as good or as frequent sales as Steam and it only serves up EA games. Dunno about uplay; I'd never have had more than one digital distribution platform installed if EA hadn't forced my hand with the release of ME3.
How does Steam #### on tablet users? It should install and run just fine. If your tablet can't run a game it's simply because it doesn't meet the hardware requirements. Honestly, do you expect your tablet to run Crysis? Now, if you're talking about them not supporting Windows 8 RT, that's a whole different story. Again, it's a hardware issues, but in this case the only way you're going to get anything installed on it at all, regardless of specs, is if it goes through the Windows Store.
The initial plans as announced for GFWL included paid MP, the consumer backlash was immense as Microsoft never really made any effort to explain why this was needed or advantageous for users and PC users had never previously needed to pay for access to MP. The marketing behind it was... not very well thought out at all.
The uptake was nonexistant, and MS quietly discontinued paid multiplayer within a few months of it being started and nothing has happened with it since.
GFWL's failure was... well, it never really offered anything for users. It was poorly cludged into the games, and was always a little awkward to update. You'd install GFWL... and it'd immediately ask you to update, you'd update... and it'd want to update again. It just wasn't well thought out. And aside from XBox achievements... it offered no benefit to users.
So users got XBox achievements, but... that meant little to non-XBox users and in exchange they got the poorly maintained GFWL awkwardly bolted onto games and other minor annoyances like encrypted saves etc.
Microsoft was entirely focused on the XBox and one assumes they didn't feel there was money in supporting PC gaming, especially after the initial paid GFWL plans died so quickly. So GFWL was never much of a concern.
And hence the door was left wide open for Valve, who walzed in and quickly became the dominant force.
From there... well, unfortunately for MS gaming on PC turned out to be more profitable then they had evidently expected.
As for Steam and touch support.... eh, Steam itself has a few touch capable games and the client does have Big Picture mode which is adequate enough for touch usage, but it's obvious it's not much of a focus for them. Big Picture is primarily intended for TV gaming from a distance with a gamepad. And the basic non picture mode client sucks for touch.
I doubt Valve will ever bother focusing much on touch beyond making sure basic bare minimum support is there.
If Valve focused more on touch gaming then they might encourage touch support, and if people use touch more prominently their liable to use Metro more frequently, since it's far better for touch then the desktop. And has an abundance of apps designed first and foremost for touch.
Since MS has a defacto monopoly on all sales of Metro apps, any significant uptake on touch gaming is a disaster for Valve. They have every financial incentive to hope that touch doesn't take off on Windows, and the mouse/keyboard and/or gamepad remains the primary gaming input device.
The Steam store is incredibly profitable for them, far moreso then their actual game development business is so anything that threatens that (and touch absolutely does, since their prohibited from selling Metro apps and Metro is much more conducive to touch usage).
I'd be shocked if Valve ever did a thing on WinRT or paid much more then lip service to the idea of making Steam any better for touch then it already is. No benefit for them in helping touch gaming on Windows.
For Microsoft, I don't think they make much effort on desktop gaming going forward. They have XBox as the primary focus, and their probably far more concerned with competing with Apple/Google for touch gaming on phone/tablet then trying to budge Steam from their position. Steam is too firmly entrenched, too popular, and Microsoft's own reputation too poor after the GFWL debacle for that to make sense from them right now. Besides, a more successful XBox can draw gamers away from gaming on the desktop and more Metro uptake could do so as well. Both of which are more profitable for them anyways as they get money from every sale of a game on Metro/XBox, something which will never be true on desktop. The ideal outcome for them at this point is probably to simply hope they can marginalize desktop gaming, giving it just enough support to ward off any threat from OpenGL (cross platform API, and hence something MS needs to discourage adoption of as much as possible as it would ease porting to non MS OS's) and Linux/Steam machines/OSX etc from taking desktop gaming away from Windows.