I've got a crumpler daily 600 and it's an excellent bag. Takes my Canon 400d, Sony video camera, 3 lenses, batteries, chargers for both cameras, all my cables plus my 15" MacBook Pro and megasafe adaptor with room to spare
But do you ever actually use this bag? What I mean is, let's take a typical photographic situation. You know someone who has a dog and you want some pictures of the owner playing with the dog. Do you take the video camera, three lensesa 400d, a computer and assorted chargers down to the park? Most likely not. Most likey you's jut take a wide angle zoom and maybe a flash for fill-in if the sun is bright and leave the big bag at the house or in the car No one runs around chasing a dog (or kids) with their chargers, spare batteries and computer.
I figure if you are going to leave the big bag in the car, house, or hotel room and I'm not going to carry it around I can use a crush, dust and water proof case.
If you are traveling the cases really are better. I've put my case put in a stake bed truck under a "b-zillion" other cases and rather roughly unloaded. As bags get bigger you will find you can't (not allowed to) hand carry them and unless you can argue well in Japanese (or spanish or whatever) you just have to go along with the rules. But even at home and in my own van, I really do not want to have to care that my camera gear is loaded on top of the stack of luggage and sports equipment. If the camera is in a Pelican case the scuba tank is ok to go on top of the photo stuff. I don't have to worry. Once I'm where I want to be I use a small bag that holds just the 1 to 3 items I'll need. The rest of the gear stays in the case.