If you want a simple answer. Some people just take the games way too seriously. Just look at the Smash Bros community.
With ORAS. The majority of them are just having their online tantrums because gamefreak decided not to spoon feed their sweet nostalgic battle frontier to them and tried something new like the Delta Episode. Some are also triggered that they tweaked up the story and characters differently to the original, even though in the beginning they were begging for trainer customization to migrate onto the Hoenn trainers who were iconic visually to gen 3, which they also didn't get into the game. Even seen a few people complain about Super Secret bases because you can make it like a gym but not give out custom made badges. They do all this while gamefreak make it rain while having pockets filled with their money because in the end they still bought it. ORAS was a fun game and made really great sales just like X&Y.
I can see some understanding with being a bit disappointed with X&Y though. Felt it did fall a bit flat in some places. Still consider them alright games and enjoyed playing them seeing how previous Generations have done worse like D/P. Platinum was the only thing that did it some justice by being the installment with added improvements and bonus post game to D/P, and some even still consider that a stretch. So in comparison X&Y did pretty nicely and gave us exactly what we should expect in a pokemon game, more or less.