Well, if Sony just moved all their exclusives to the holiday season, they would have a great holiday line up, as well. Instead, they prefer to keep the momentum up throughout the year, which is the smarter thing to do.
Of course, this thread is a bit premature anyway, since we need to wait til E3 to see if Sony has something for later this year. Which I'm sure they do. There's also the price cut, which if it is truly the $100 price cut some think it will be, will mostly nullify the sway of those games.