As someone mentioned before, Sony probably takes a hit offering free online service all the time, while xbox charges. All of my friends say that Xbox's service is way better than sony's...but if that's even true, it's only because they have a higher budget because of the paid subscriptions. If Sony wants to make their online experience better than Xbox live, they're probably going to have to start charging.
That being said, I think Sony's move as a whole is pretty smart. If they charged the whole populous, then there would be an uproar and they would probably lose a lot of gamers (even though Xbox has been doing the same thing for years). Instead, they're leaving the research and development up to those who want to invest in such.
I realize that the cross-game chat function may be important to a lot of people, and perhaps it's not the best perk to throw in with the paid amount, but maybe they're also doing that to boost the paid subscriptions when the other features come out.