Hm? The term "Grand Prix" has been in common use for open wheel non-oval events since I don't know when. I'm not sure why, but I guess it was/is done in order to distinct the road/street races from the oval races. I must admit though that the Mid Ohio race wasn't labeled "GP", but "Mid Ohio 200" or so. What's the big deal?
And were there really that many rookies? RHR was the only guy new to the IRL.
And what's wrong with road course specialists? Some do better on the road, so do better on ovals. I think it's great to have a certain mix of both kind of racetracks on the schedule so in order to win the title you must be skillful on both.

I don't see how this can confuse a casual fan.