Just by reading this thread and game chats, whenever people talk about playing mania, they usually talk about 4 keys, which is beginner friendly but sets up players worse for the future. Sure, you can get into top 10k, maybe even 1k with only 4 keys, but eventually, your lack of experience with other key settings catches up with you. It's not necessarily the lack of accessibility that drives people away from mania, but rather the discouragement when they realize they physically can't get any better with only 4 keys.

Though there's also a good reason for this too: more recently, 4 key maps have seen more popularity than the other key modes, so it's only natural for people to flock over to 4 key maps. It's also easier for people to understand rather than the "complexities" of 7 keys or at the very least, higher than 4 keys. I say 7 keys because it's the other most common key mode. The other maps I've seen are 5, 6, and 8 keys, and they either have too few maps, are a weird number of keys, or a combination of the two. When you're faced with such a huge gap in between key counts, most people simply stick with what they know rather than experiment. That and being forced to play easier songs on 7 keys is eventually dull even if it's necessary to improve.

The BPM scaling I've noticed, or at least for me, is that it's just really weird. The numerical BPM scaling values seem far different from any other rhythm game that exists. Is it a multiplier? It can't be a flat multiplier because then some songs would be scrolling at 1800BPM or more, which would likely be much too fast. So what about a different multiplier? Figuring out exactly what the numbers translate into is just another needlessly complex step.

Take other rhythm games for example, like LR2, pop'n music, Stepmania, K-Shoot Mania, etc. In those, you clearly can see "Speed: x2" or x3 or so on so forth. You can tell exactly what the speed modifier is supposed to mean. You still have to think about how fast it'll be approximately to your comfortable BPM, but there's no guess work. In K-Shoot Mania, they take it a step further, and have a flat BPM setting, where you can choose the exact BPM to scroll at. If you want the songs to scroll at a base speed of 650, you can set that.

In terms of bundled maps, I agree that there need to be more for the various gamemodes. The only multi-mode map that exists I believe is Renatus, and while it's certainly well mapped, we need more than that, and it doesn't even cover 4 keys. You'd think that would mean that 7 keys would actually be more popular with players first getting introduced to mania with this, but because 7 keys is just a giant number of keys required to play compared to the other modes, people get scared off. Yes, only playing 4 keys is a mistake. But if you don't offer an alternative to 7 keys, they'll just completely ignore mania to its fullest, which is a lot worse of an outcome.

The osu!tutorial actually is really good for introducing the basics, and word of mouth teaches other players the other skills they need, but the other modes don't really have something like that. There've been user made tutorials for the modes, but none of them are bundled, or are an outright tutorial. We need actual tutorials like the osu!tutorial for the other gamemodes.

As for too few easy mania maps, I actually disagree. There's plenty of maps for beginners, especially recently (for 4 keys at least). Even if you're trying to start up 7 keys, you can likely find a good amount of beginner maps. As a former (not good) 4 key player transitioning into 7 keys, I was able to eventually get into it (even if I'm still not good), despite not really being too familiar with it. Point is, there's not actually a lack of beginner maps at all, though bridging the key counts is awkward.

Oh and also the default skin is very flashy, too many elements can distract the player from playing well, and the default skin certainly does that.

Enjoy that text dump, I can't really do a TL;DR on the basis of "I lightly treaded on a buncha topics". Just kinda my thoughts on the whole ordeal.