How is it actually inadequate though? Honestly now?
Um, I listed about 4-5 reasons in my original post on why it's inadequate if you care to know, and none of them were "not every game supports it." In fact, that's the recurring problem with Big Picture: there are no support features for games to integrate. It's just a Store and Library browser, nothing is different than when you otherwise plug your PC into a TV.

Something being improved in the future doesn't curtail criticism of it now. And no, you can't mandate developers to integrate features for past titles. A lot of games coming out today still don't have Steam Achievements or the in-game Shift+Tab interface. That does not bode well for the big incentive to use Steam: the ridiculous deals on recent and older games. Most of the allure of a Steam box dissipates when all of its library up to the launch does not integrate well.

I'll try again for a fourth time: Big Picture's official release makes me skeptical of Valve's ability to execute on its console ambitions.