Some days, I think I'd rather gouge my eyes out than read another email about a new roguelike or roguelite. This confuses me, because many of favourite games are roguelikes or roguelites, including Dead Cells, Balatro, FTL: Faster Than Light, and the recent Morsels, a reeking procedural dumpsite that speaks to the overproduction of Rogue/rogue derivatives at large.
Roguish games are everywhere right now. According to SteamDB, 1602 games tagged "roguelike" were published in 2024 out of 18567 total, versus 312 out of 9655 in 2020. Stir in roguelites and the countless games that advertise themselves as having "roguelike mechanics", and I sincerely worry that you're describing the majority of PC releases from the past couple of years.
Then again, how many of these games are 'genuinely' Roguish? Roguelike and roguelite have become such broad concepts as to be functionally useless, describing everything from carpentry to casino machines. This was the case back in 2011, when Adam Smith (RPS in peace) marvelled over a peculiar new "Roguelike arcade game" called The Binding of Isaac; it was the case in 2016, when Alice O (RPS in peace) observed that the term roguelike is "so very bendy and too confusing to throw around without explanation".
Personally, I define these games as follows: a "roguelike" adheres more closely to the original Rogue from 1980, featuring permadeath, equipment or character progression, procedurally generated environments, and semi-randomised challenges. A "roguelite" is a less harrowing variant that may not have an explicitly defined rogue character or dungeon - in particular, it may feature an over-arching system of unlocks that persist between runs, taking the sting out of restarts. Still, perhaps a more useful way of thinking about roguelikes and roguelites isn't to tick off correspondences or take them back to their roots, but to look at the shapes they form within the greasy currents of platform economics and player habits.
The popularity is because they are easy to pick up and put down. If I want to go back to an RPG that I haven't touched on months I need to try to remember where I was going, what my build was doing, and how to deal with the things I was fighting. If I want to go back to FTL that I haven't played on years I just start a new run anyways, and all my ship unlocks are there if I want them.
I would argue that a substantial reason for their popularity is also just that devs have fun when developing them.
With most other genres, you've seen the story a gazillion times, you've done each quest a thousand times etc.. It just gets boring to test the game and it becomes really difficult to gauge whether it still is fun to someone who isn't tired of it.
Meanwhile with roguelikes, the random generation means that each run is fresh and interesting. And if you're not having fun on your trillionth run, that's a real indicator that something needs to be added or improved.