Yeah, we're unfair.
But we collectively pay their bills, so we get to be unfair. "It's not fair!" is the reaction of a child. Yeah, it's not fair. Consumers/users/fans are not really fair. They never will be -- they never are! Is it fair that Two and a Half Men has a series run longer than Firefly? Is it fair that east Africa is in the midst of a generational drought? Is it fair that your friend is better at Magic: The Gathering than you? Is it fair that D&D has so many more players than the Star Wars RPG?
Heck no!
What is fair is irrelevant. The world ain't an equitable place, and it's utopic to insist that it must be. One of the challenges of any company that wants to sell stuff is to figure out how to deal with the patently unfair environment they're selling stuff into.
I truly hope you do not believe this. It is
one thing to acknowledge that the world is inherently an imperfectly fair place due to factors beyond our control. It is
another damned thing entirely to use that as justification or an excuse for behaving poorly, which is what you're doing here. Yes, the world isn't fair. Does that give you, or anyone else, license to act like a brat? No.
What is fair is
not irrelevant.
This hinges on two things.
First, what you mean by "okay." Is it logical and rational? Not a chance. But it's not logical to feel like the thing in the pink box is more feminine than the thing in the blue box, either. So "being logical and rational" is really an irrational standard to hold any random person to (including any random person crying about how 5e is the devil on the internet).
Again, as above: it's one thing to point out that people are inherently irrational. It is another thing entirely to use that to justify behaving in an irrational manner about something you should approach with rational thought.
So it is "understandable," in that this is demonstrably how people are. There is an emotional investment in a brand. That's part of the POINT of a brand, after all. It's part of our personal stories and our personal histories and these things get associated with strong emotions and so get expressed often in emotional terms. So is it permissible on, say, a message board about D&D, to post an emotional opinion about how you don't like 5e? Sure. It's "okay." Here at ENWorld, we take a bit of a dim opinion of overwrought venom and acrimony toward a given game, but this is mostly because it makes for lousy conversation, which is what the board is ostensibly about. It's not necessarily because people shouldn't think that way -- get a blog.
Second, the formation of that less-than-flattering opinion of the opinion implies that your own opinion is somehow more "okay" than the other.
I'm going to say something now that
shouldn't be controversial, but apparently
is controversial to certain people anyway: Some opinions are more supportable than others, and some opinions should be given less respect than others.
But, because people aren't logical and rational, that's probably a false sense of superiority. A passionate love of 5e is just as irrational as a biting hatred of 5e.
I would argue that it's not, actually. A passionate love for 5e reflects an appreciation for the game and a desire to play it, which will likely make the game more enjoyable to play. Meanwhile, a biting hatred of 5e reflects a fixation with something that you purport to want nothing to do with, and serves no productive purpose whatsoever. It demonstrates that you value tearing something down more than building something up, and that you'd rather spend your time on being negative about something you don't enjoy than being positive about something you do.
It's not more correct or better researched or more defensible, so decrying others' irrationality is a vicious double-standard and a possible self-delusion. "Your opinion is dumb, my opinion isn't" is always false. We also take a pretty dim view of THAT here on these boards, for much the same reason: it's lousy conversation.
Again, the notion that all opinions are equally worthwhile is a false one. It's understandable that some would want to push the notion that they
are equally worthwhile, if their own opinions are being repeatedly shown to be unsupportable. Making opinions immune to criticism certainly goes a long way in evening the playing field for the people with poorly thought-out opinions.