>>27310475There was a name for this concept but I'm both too forgetfull and too lazy to figure it out, but its based around the fact people look at stuff from when they were young in a much better light than they really were. Most people forget the nuisances and minuscule details that piss the off now, and only remember the excellent and trully remarkable factors. Its natural in humans, and I think that can be atributed to pokemon. People who played it as kids forget how confusing it could seem at times, how many pokemon were what they now call uninspired, lazy concepts or just bad designs, and just how much bad stuff the original games had, because the good stuff was just so much more important to them, those memories of the nice aspects stuck with them far longer. Now they have an unrealistic image of the first gen, leading them to have too high espectations and it results in them being mad when in reality its just as good as, if not better than ever.
You can see this happen with anybody's favourite game: hoennbabies forget how awfull the older pokemon distribution was, how horrid the water segments of the region were, and designs like (incoming opinion) roselia, mawile and torkoal. Sinnohfetuses forget the horrid swamp, the awfull overall speed of the game, and the shitty as hell initial pokedex. Because every game has more good than bad.
At least we can take comfort in the fact these complaints aren't just blind hate, but come from a place of love, and of a desire to have pokemon be better and better every time, as misguided as they might be.
TL;DR: They've forgotten the bad, and just want pokemon games to be as good as their fragmented memories remember them to be