I wouldn't say the downspecs is because of ps3, it's because an mmo based on looking good with no substance is just stupid lol The high intensity graphics set for high end pcs alrdy alienates over 75% of the playerbase with maybe 5% being able to play the game and the other 20% willing to let their comps overheat by the high specs.
This "downgrade" in specs should allow them an easier time to produce content for the game as well as make more unqiue zones rather then a lot of copy and pasted stuff in each region.