This amused me. You think people who play sports as a hobby don't judge each other on performance (even when they are on the same team)? Same could be said for card games, collectors, knitting, hell any hobby where more than one person does it.
As for the subject at hand. Those of us that have been playing longer are not necessarily better players, we probably have more experience of the game in terms of time played and we certainly have seen more changes to the game than those that stared more recently. Does that make opinions more valid? Not really. It's not like those who have played that long share a common opinion. For example I don't buy into the whole Burning Crusade was the best expansion and the raiding was awesome that seems to be a commonly expressed viewpoint. Or at least loudly expressed. I personally think the game is better than ever right now.
Is it perfect? No. Do I like all the changes? No. Would I go back to play an older version of the game? No.