Center channels are very helpful in teh case of odd listening position form the TV/display. Thats when a center channel comes into its own. But if the geometry is setup properly with the mains flanking the screen equidistant and if the listening position is also centered witth respect to the screen, then a center channel is most definately NOT required. I was fortuneat that in my old home, the geometry was perfect. I had to remove the center channel while trying to sell my last home and I did not miss anything. Thats becuase my mains imaged so well and anchored the sound to the screen. But like I said, I had the geometry set-up perfectly.
Yep. Most of us are not so fortunate. When movies are going at my house it's usually me, wife and 2 kids. Add in the in-laws that are coming to town and we have a large audience spread all over the room not anywhere near the sweet spot. The center helps make up for the wild angles people are sitting at.
And for those that say the center has a negative impact on sound, or that it "just can't handle" 60% of the soundtrack ... phooey. As always a lot depends on what speaker you have up there. I've got a Paradigm 690 which is a 6 driver beast. It's capable of handing (virtually) anything the towers could have done and it creates a huge hole when it's absent (I tried it). If you put a bose cube under your TV

then of course it won't sound right. (ok, I might have gone too far with that Bose comment).
I've found in my room you can compensate for that by bringing the towers in closer but then I get a noticeable gap between the front and rears in my 5.1 setup.
Bottom line - Speaker placement, whether you need a center ... these types of questions we can give you guidance on but so much depends on your room none of us can answer with certainty. If possible, find an A/V buff locally that can come over and give you sound advice. maybe even drop some equipment off to play with.