Here's the problem Valve faces - All the major tablet platforms (iOS, Google Play, KindleFire/Android, Win8 RT) have app stores dedicated for that device. Some allow side-loading but that freedom could quickly disappear.
This means a number of things: 1) Valve is late to this game and is fighting entrenched existing app stores that sell tons of games 2) Pricing is an issue as these app stores don't really have high ASPs on games - tablet users are cheapskates compared to PC gamers 3) The form factor is wildly different, making it tough/nearly impossible for Valve (and devs) to port. 4) The freedom to side-load for those platforms allowing it may lose it at any time (see: google play services)
All of these mean that tablets are not exactly fertile ground for Valve/Steam. As far as they're concerned, the PC (and Linux) is where it's at (I still think they could out-do Ouya/PSVita with a steambox, but seems like the idea is either a non-starter or ahead of it's time).
This means a number of things: 1) Valve is late to this game and is fighting entrenched existing app stores that sell tons of games 2) Pricing is an issue as these app stores don't really have high ASPs on games - tablet users are cheapskates compared to PC gamers 3) The form factor is wildly different, making it tough/nearly impossible for Valve (and devs) to port. 4) The freedom to side-load for those platforms allowing it may lose it at any time (see: google play services)
All of these mean that tablets are not exactly fertile ground for Valve/Steam. As far as they're concerned, the PC (and Linux) is where it's at (I still think they could out-do Ouya/PSVita with a steambox, but seems like the idea is either a non-starter or ahead of it's time).