On topic, I think "casuals" get a lot of hate because, for better or worse, the casual market dictates what the broader gaming sphere will look like for the foreseeable future.
The Wii was a huge hit with "casuals." This led to a 2-3 year period where Sony, Microsoft, and lots of triple A devs crapped out shitty motion control shovelware and little else.
Casuals glommed onto Clash of Clans and Candy Crush. All of a sudden, nearly identical microtransactions and wait timers are shoved into major game franchises. Repeat for lootboxes.
Hell, if we're talking about the mobile market, we may as well point out that the "casual" market has basically destroyed that entire landscape. It's hard to remember how promising mobile gaming's future looked in the early 2010s. Now it's basically just half cooked ports and shameless whale hunters.
These are all broad strokes, but they speak to the larger problem. A more casual audience is going to be more willing to overlook problems with, and exploitation in, their games, as they simply don't care as much. And many developers, cloying trendchasers that they are, are willing to capitalize on that. This is not a problem with the casual player - it's a problem with the shitty industry.
And the reality is that it infects mainstream franchises, and that pisses off the "hardcore" crowd. Sports games have effectively stagnated and just become vectors to hock slot machine lootboxes year on year. Battle passes got popular with casuals, so every mainstream arena shooter now has one. Diablo and Dungeon Keeper players starved for a new game? Don't worry, they're covered: here's a shitty mobile game clearly built to slowly milk your wallet. Let's strip well-loved post-game features from Pokemon because "kids have cell phones and don't have the attention span for it," per the developer. Dead Space 3 and Resident Evil 5 have to be a generic action games because survival horror isn't popular with the casual crowd. And I guarantee that something like Suicide Squad wouldn't have gotten NEARLY the amount of shit it did (still some, it wasn't good, but I digress) if it didn't feel compelled to drag the poor Arkhamverse down with it.
And while yes, there are lots of games being made, I think it's unfair to just expect the extant player base to not be upset about seeing franchises they live make these turns. Sure, there's alternatives; the gaming sphere is huge. But if, for example, Dark Soulsn4 was announced, full of microtransactions, a Ubisoft HUD, a battle pass, and a story written by Shigeru Miyamoto... I wouldn't just say "yeah just play Hellpoint, it's closer to the Dark Souls you want." Because the player doesn't WANT to play hellpoint. It may be FINE, as an indie Dark Souls knock off, but that player would always be happier with an actual Dark Souls 4, because it's a storied series they're already invested in.
And again: NONE OF THIS IS THE FAULT OF THE CASUAL PLAYER. People like what they like, the way they want to like it, and that's not wrong. All the problems with "casuals" are a case of misplaced blame; the fault lies with publishers/developers, who look at something successful and always learn the wrong lesson from it.
Doesn't take a lot of brains to be a good fighter.