Here's my 2 cents worth... sorry ST1100, may not be exactly related to your original post but thot I'd contribute something quite on the topic...
For something as fleeting and where you got to think on your feet, you can't beat a zoom lens.
Of course some photographers will lug around 3 cam bodies and all that but that doesn't mean you should do so. I think experience counts also for you to know what you want to shoot.
You should not compare a sports photographer who carries heavy 400mm or 600mm lenses, and then think, so for wedding I also must carry at least 2 big lenses (not of the 400m/600mm kind though!) if not more. Got to compare apple with an apple.
The problem is, amateur photographers (like me!) sometimes go overboard and want everything, wide angle shot, close up shot (even macro!!), low light shot, etc. So they even bring their 50 f/1.4 prime in addition to 28-70 f/2.8 giant and another 70-200 mm giant and even maybe throw in a 20-35 f/2.8 or a 24mm prime. Very confusing indeed.
I think in photography, focus (no pun intended) is very important. You really have to decide what kind of shot you really want to include or portray. You can practically use any lens from fisheye to 400mm for a wedding, say. But question is it practical?
I went to a seminar given by a National Geographic photographer once and he commented he was amused at how many lenses amateurs tend to bring for their photo shoots. He said with so many lenses to change and all that, you'll sort of lose concentration and maybe that exact moment. For him, yes, of cos he has more than 1 body and of course, more than 1 lens, but they are mainly f/2.8 zooms. Changing lenses is not quite his cup of tea. But then again, he has the luxury of assistants to help him.