Bikeshedding as a protection bubble

There is a thing called bikeshedding, and if you've ever been in a meeting or on a mailing list where a group of folks are trying to make a series of decisions, you've seen it.

What I wonder about is why bikeshedding doesn't keep dumb things from happening. Why is it that instead of making it so people give less energy to accomplish difficult tasks, they don't put it off until later. That seems like a better option.

I could hand wave it as human nature, but I'd like to think it is something we could train folks to do.