Blanket statements are wrong. There, I said it.

I'm with bobwysiwyg, taking a good picture is much easier to take when stopped. I'm not saying it's impossible to take a good picture while rolling, but you're far more likely to get a snapshot (I'm old enough to think "Brownie camera") like that.

And I'm also with woodcraft, when I'm coming up to a congested intersection in heavy traffic, that's no time to be drinking out of a water bottle.

And indyfabz is right too, if there's one other cyclist and nobody else on the road, there's not much need to worry about traffic.