Speaking to Chuck Klosterman in yesterday's Guardian...

"It seems simple to me," he says. "It just feels like this should be the last one. For one thing, I always told myself I wouldn't do LCD past the age of 40. For another thing, I don't know if EMI would put another record out by us. They've been very good to me and they've never tried to force me to create a hit, and everything people have told me about signing with a major label has proven untrue. But the way the industry is going, EMI might not even exist in three years. And a third factor is that I really want to do a good job, and I want to do everything myself. Now, I could have other people do some of those things for me, but then it's not really the band I want. The only reason I would do that is because this is a business, and that's not a good enough reason … It seems like something I didn't want to have happen did happen: I see this band as pure evidence that having a decent idea is more important than being talented."

http://www.guardian.co.uk/music/2010/apr/24/lcd-soundsystem-this-is-happening

So, partly it's an age thing, partly it's because anything under the LCD moniker would be owned by Emi? Seems logical tho.