I don't think a crate is totally necessary all the time but it depends on everyone's situations. They can be GREAT and I wish Jackson was crate trained but it didn't work for us. I was really lucky that I got Jackson in winter of '08 when I was off on winter break from college, so I had a whole 4 weeks to be with him solely. We had a really great schedule for a long time and we did use the crate in the beginning... I would place the crate on my bed and he would sleep in it, he woke me up around 3-4am to potty, then we'd wake up again at 7:30am to go potty again, then he'd get 30 minutes of play-time but only in the 1 room where I could watch him 24/7, then we'd go back to bed until 9:30ish, and when I left the house, I'd put him in his crate while I left. Then after a few weeks, we moved up to the expen, then locked in my bedroom.
But anyways my point is I had a really consistent schedule with him in those first few weeks where we did the same thing every single day. He's had free roam of the house since about 4 1/2 months old and never once has he had an accident while we're not home or chewed anything (he had accidents when we WERE home of course) and I call him 99.9% potty trained. He will occasionally poop in the house still maybe like once every 2 months and it's usually when it's raining outside or something!
But you can get thru it.
Potty training days are tough!