The problem is that most people rate the first way. If a place has a rating of a 4.5 and I thought they were pretty good, but not perfect, so they deserve 4 stars, I am not going to rate them. Having 4 stars is usually considered not that good, so lowering their score is not what I want to accomplish as 4.5 is pretty fitting in the context most people have.
That leads me to giving 5 stars relativley often and not rating ok or just good places at all.
The problem is that most people rate the first way. If a place has a rating of a 4.5 and I thought they were pretty good, but not perfect, so they deserve 4 stars, I am not going to rate them. Having 4 stars is usually considered not that good, so lowering their score is not what I want to accomplish as 4.5 is pretty fitting in the context most people have. That leads me to giving 5 stars relativley often and not rating ok or just good places at all.