As far as I've read, sony's got plans on making online subscription based as well, maybe just for the ps4 though who knows, I've only read very little regarding.
Either way, it's not really surprising for a lot of things these days to be subscription based. To add to what someone else said, people spend hundreds of dollars a year on game like WoW, and don't complain xboxlive is only like.. $5 a month. The argument about buying the console and game therefor playing online should be free doesn't apply.. People buy PCs, pay for their internet service, buy the game, and still have to pay to play in a lot of cases and that's only for one game, a lot of people play several. No complaints there. Why?
Again, like someone else said: You get what you pay for, and the quality of xboxlive is pretty worth it for $5-$10 a month.