I don't really have a problem with owning a locked down STB and I doubt their security would be anything other than a handwave for the publishers. PC STBs are awesome, I have a Zotac AD10 running Windows 7 for XBMC in my living room. I already play emulated stuff on it, might as well make it a proper Steam box too.
I have my desktop PC for flexibility and for things like modded games. You largely won't be playing big name releases on these things anyway, it'll be smaller, indie releases and I doubt the DRM would be anything other than what Steam already has.