I guess Sony doesn't bring RTS's to the PS3 because they're waiting to see if Microsoft do it well with their console.
Also, you have to remember, they are competing against a company that basically owns the PC gaming Market (thus having all the connections to popular PC genre's i.e RTS) so they would have a tougher time getting developers to work on a untested Genre for their console, where as Microsoft would probably have it easier because of the relationships it established via the PC already (Supreme Commander, World in Conflict, C & C etc).
I don't think RTS's are impossible for the console, obviously it won't be as good as a PC, but it's not a broken system either. Think we'll have to wait and see what comes of Halo Wars and The new Tom CLancy game (think it's EndWar?) to see what the future holds for Console RTS. I didn't include the Wii because the point and click functionality makes for a totally different experience, but it is basically guaranteed Nintendo will make another Pikmin game.







