Let's check in with how Sony feels about this in 12-18 months. These consoles haven't even been out a year, so OF COURSE the catalog of games isn't very big yet. If EA were to round up all those old DOSbox emulated games they sell on GOG, and emulate them on these new pc-based-consoles, the back catalog of games would increase more than 1000%. The value proposition would then be a no-brainer.
edit: Honestly though, these services that offer "free" things are probably just going to lead to a bunch of entitled bitching when the monthly selection happens to be weak.