It’s a financial decision. Building a competitive console game wasn’t cheap by that generation, and passion only goes so far. Publishers ultimately want to recoup their investment, which means developers targeting the common subset of functionality and using middleware wherever possible to support multiple platforms. Unless Sony was your publisher, it wouldn’t have made economic sense to deeply optimize for Cell. PS4 and Xbox One being so similar to each other is good for developers, which is good for games, which is good for gamers, even if it does mean fewer esoteric toys for passionate engineers to play with.