SaaS is not a panacea. It's still a long way from being a completely viable corporate solution, much less for end users and gamers.
Make something worthwhile and people will pay for it...
Unless you are Penny Arcade. Those guys produced a game that was geniunely fun and engaging, and was pirated in-so-much that it was not viable for them to finish the series.
I digress. For services like that to work well, you would need numerous well placed servers. Google has the right idea with their data center in a trailer approach.
Even if SaaS was a mature enough delivery platform, the US lacks the infrastructure for the majority of the rural US to get any use out of it. So long as Big Cable/Phone can charge $55/mo for 3mbs, then there is not much that can be done.