Of course it's a fair opinion to hold, but would you not agree that it's less confrontational to simply say "I prefer the game the way it used to be" than to say "the game isn't what it once was."
I, for one, play Fourth Edition. I don't want to go back to 3e (or 2e, 1e or Basic D&D) for all sorts of reasons, and no amount of arguing is going to change my mind. Similarly, I accept that some people prefer those editions and aren't going to play 4e.
What I take issue with is people who refuse to give 4e a chance, or cast aspersions on it without playing it. I had my issues with, for example, Castles & Crusades, but I gave it an honest try. I don't want to try Pathfinder because it is, by everyone's account, largely a modified 3e. And since I don't want to go back to 3e, I don't want to try Pathfinder. However, those are, on my part, informed decisions. I'm operating from a space of knowledge and experience - not supposition.
Anyone who gives 4e an honest try and then says "nope, sorry, not my cup of tea" earns my respect. I may still agree to disagree with things they like or dislike about the game, but they're entitled to their opinion. I enjoy, and even look forward to, an honest back and forth about the relative merits of different editions with such a person. And all the while I recognize that we may perceive the same issue from different perspectives.
I realize that not all fans of 4e are as tolerant. But given the amount of vitriol many (most?) Pathfinder and other older edition players toss their way, I hardly find it surprising.
Play what you like. It's when people go about trying to justify "why" they play what they do that someone gets insulted, and a fight usually starts.
Again, my two cents.