I'll throw my own zoomer opinion in. It is important to draw a distinction between the pre-iPhone era and the post-iPhone era. There is a massive difference between the older Zoomers (1997-2005) and the younger ones due to how much the iPhone impacted how people function and think. As an example, I didn't get my first smartphone until I was around sixteen, and even then I didn't have unlimited data as it was still to expensive for my family to afford. I spent my entire childhood reading books, and while this obviously wasn't the norm for children even prior to the release of the iPhone, there is an evident difference in general intelligence and attention span between these two groups. As a disclaimer, both groups are filled to the brim with low-IQ degenerates who are being manipulated/brainwashed by the oligarchs that run the West, so even if we fix the following issues, I doubt it would do much good.
When it comes to Zoomers from the pre-iPhone era, there are many reasons why older RPGs are not popular. An easy one to start with is that many people did not grow up playing those games, and are thus unfamiliar with the genre. I distinctly remember young Chon being drawn to third-person/first-person games and being averse to isometric/top-down views (although I grew up playing a ton of Rise of Nations which was awesome and I begged my parents to buy me SC2. I never got to play it since our computer was incapable of running it, but still). It sounds strange to say this since now almost every game I play is isometric/top-down, but they really are a sort of "acquired" taste, and one really needs to devote a little time until they get accustomed to it, likely because it requires a higher level of abstraction compared to other types of games. Plus, strategy/tactics games are some of the most common types of isometric/top-down games, and these are harder for younger kids to enjoy/get into for obvious reasons.
Once someone becomes familiar with the genre, many older cRPGs are, well, old. They can be difficult to get running, low resolution, clunky, and hard to get into. To this day playing games in DOSBox feels like absolute shit for me, and it's a shame because I know that if it wasn't for the fact that they are DOS games, I could probably really enjoy them. As others have also pointed out, there are many things in RPGs which really aren't that intuitive, and can lead to people bouncing off. Making a character without looking up a guide for example. It is actually not that easy, we're just so familiar with the genre it feels that way to us. Getting lost and not knowing where to go and/or what to do are also things that commonly happen in older cRPGs, and they happened to people who played said games at the time. They just didn't have any alternatives so they dealt with it.
When a prospective cRPG enjoy overcomes these two obstacles, then the issue of advertising/popularity comes into play. Many people have simply never heard of classic cRPGs, I know I hadn't, and even when I did discover the IE games, I wouldn't have found out about many other classic cRPGs without the existence of this website. Outside of the RPG Codex, I feel like the idea of a classic, old-school cRPG doesn't really exist. It's so weird that so many people are completely clueless about the existence of games that used to be so popular. Plus, we don't even have new game sbeing released which are similar to old cRPGs. Isometric cRPGs and blobbers are basically only a step above being dead in regards to new releases in general, much less massive triple A studio releases.
The post-iPhone era is completely fucked, and we shouldn't even bother trying to ask what we can do to fix these. These kids brains have completely atrophied, and they are barely capable of basic mathematics, proper speech, and simple writing, so you can forget about them playing/getting any game with a modicum of complexity. The West have done an amazing job of securing their future, as future generations are assured to be mindless consoomers (and that's a generous classification).
TL;DR
- Zoomers did not grow up playing video games that are similar to old school cRPGs, making them naturally averse to trying those kinds of games.
- Older cRPGs are more difficult to get into in terms of game design, general clunkiness, and technology wise.
- Many people have completely forgotten about older cRPGs, and the cRPG genre itself is pretty much dead outside of niche indie titles.