I had a 1995 Powerbook, a 2005 iBook and now I have a 2007 MBP, all with a non-flush bezel and I've never had a problem with dirt between bezel and screen, just as I've never had a problem with cleaning the (unprotected) screen itself. These days I'm going to buy a MBP 15" with matte screen... it's not as if there's a giant gap.
I can see how dirt underneath the bezel could possibly become a problem but a sensible amount of care should help to avoid that. It's also a question of the environment you use the laptop in. I've used mine on and off music and theater stages, in rehearsal rooms, hotels, offices, cars etc. and at home - all in all indoors mostly, not necessarily controlled spaces but indoors. Would I use the computer mainly outdoors, I'd probaby appreciate a flush glass front. With matte film, that is. 😉
troop231, do you have a dirt-bezel-screen-problem with your current laptop?