I completely agree with both of you.
Seeing how many fans end up being disappointed by every new game, it is probably better to have low expectations instead of setting them too high. It seems many people always have a vision of how something should be in the next game, only to have it ruined completely because their expectations were too high or different from what the game turned out to be. I do personally never participate in pre-release speculation for this reason, no matter what you might speculate will be in the next game, it is likely not going to be there. Starting from B/W, I have had rather low expectations on new games for various reasons, and I have pretty much only been met by positive surprises. Speaking of expectations, I have practically no expectations on OR/AS right now, but that's not belonging here. And since this thread is about disappointments, this is one. Not about the Pokemon franchise itself, but rather about the fandom. But as both of you said, this seems to happen to everything so it is for better or worse nothing unique regarding Pokemon fans.