I liked Tom Petty but was he ever really big over here.David Fricke (American) and David Hepworth (British) spring to mind, but perhaps it more informative to look at the list of musicians paying tribute to Petty following his death. Or maybe look at the Peter Bogdanovic documentary and see the musicians who held him in high esteem.
The comment about modern "rock n roller" alludes to the fact that his music is more in the spirit of Elvis, Buddy Holly or The Byrds and Dylan than it is with the other artists that you mention. His music wasn't of the 70s or the 80s or the 90s (even though this was his popular period) - the point is that it could have been written at any time since the 50s. There's nothing in it that ties it to AOR or punk or grunge or any other sub-genre of rock. He knew how to write a good melody, a great middle-8 and brilliant choruses. He also had a great band, Mike Campbell (guitar) and Benmont Tench (keybboards) who played with him for all of this career.
Look, we all like different artists, but the point is, Petty is not some AOR artist who came and went in the 80s. He was big from the mid-70s to the 90s and well respected for all of his career until his untimely death.