Well, yes, because the higher the PP gets, the more the races become one-make domination races.
When we had lower PP races, it seemed like the competition really opened up to some very varied car combinations. I suppose its not really an issue with PP specifically, just the fact GT5
has a larger selection of slower class cars than it does faster classes (just like the normal Gran Turismo game really).
Also, the faster, higher PP races don't allow very much safe contact racing, whereas back with Suzuki Swifts, we could have more touring-car esque battles, where we could have some contact without it completely crushing people's races. It was infinitely more fun and it seemed more balanced for everyone's driving skill.