This may sound like a drawback - certainly, a stab jacket is almost impossible to get off without releasing at least one clip. However, this is an 'apples and oranges' situation. A stab jacket relies on the shoulder straps being tightened. A wing, however, has long shoulder straps - plenty of slack is available. Like a rucksack, really: You just slide your arms into the loops, and off you go. You don't need clips.
Not only are clips not necessary, they aren't desirable either. Webbing can support an unbelievable amount of weight before it snaps - if you're capable of taking it on a dive with you, webbing can certainly support it. However, plastic clips are not so reliable. I've had a shoulder clip come undone when it was only carrying my twin 7's. And that was one of the A.P. Valves extra-strong ones! When you consider the type of strain you put on a BC with twin 12's and extra stage cylinders, you can see why plastic clips are looked down on by a lot of divers.
Usually, the only time you'll see a clip on someone's harness is when they want to be able to add extra slack to their shoulder straps. This doesn't actually put a break in the harness, just allows for some slack to be kept out of the way until needed. This adds to the harness' adjustability, without adding failure points.
