It's a numbers thing, of course some people use just about everything that's possible.

Me personally, it interrupts my flow-of-thought to think "o.k. now I want that funky character I don't remember how to get without going through some big lookup process - meanwhile, I can type the basic stuff 1000x faster...."

I also understand that for people who do it all the time, it gets easier - but the majority of people out there aren't the ones who know how to do all that.