I mean, some people may just be jerks like that, but I don’t think that’s the general thing for most of these controversial D&D rules (at least on this forum).
Instead, I believe many people see the inclusion of certain rules as undesirable because it will have a negative effect on our personal D&D experiences. An official published rule, even if optional (like multiclassing and feats), influences the general perception of the game, especially amongst new players who are less likely to pick and choose what parts to use. Tie in that AL generally uses official rules, and you get an additional entry vector. The fact is, even if you are playing in an established group that chooses not to use the rule, there will almost certainly be some sort of pressure or tension caused by it at some point, unless you wall your group off from the the D&D info-sphere and never take in new players. And in addition to the social elements of expectations, there are also design considerations. Current official rules influence what official rules are going to happen in 5e in the future. For instance, by putting the specific “Aberrant“ back into the psionic themed sorcerer it presumably (I don’t have the book yet) is more clear that it isn’t “the 5e psion”, leaving design space open for one. Or take the play test psi die. Some people loved them, but many people had concerns. They changed them into something that works for most people. And the conflict is resolved. Spell Versatility could negate future design choices that might alter the sorcerer in a way that might be more generally pleasing. It is clear (at least to me) that something is needed to improve a sorcerer’s flexibility, but it is also clear that Spell Versatility was contentious. By choosing not to make it official, they have room to come up with a better solution that is more generally desired. And that is something to rejoice about.
I definitely understand the desire to get cool new things, I just think it’s usually doable in a way that doesn’t impact on the fun of others with a bit of patience and restraint.