They've made far more complex than what you're saying.
GT6 is more basic than GT5, no course editor, not as much special events.
Perhaps GT6 is still evolving, so we should wait and see.
I bought a PS3 because I wanted to play GT6.
A couple weeks ago, I started playing GT5.
Graphics are little bit better and what about the special events.
I used to hate Nordschleife, but with the AMG driving school I've started to like the green hell.
And in the last month there were 2 really interesting seasonal events in GT6 that really were exciting to do.
The nordschleife and GT500 event. I spent a lot of time getting gold at the Nurburgring and cutting off time in Laguna.
So kudos to that!
The red bull thing is just ... a commercial step.