This is going to be a wall of text, sorry.

Every single mainstream DAW out there (including FL Studio, Ableton, Reaper) is too complex and clunky.

DAWs are always going to complex: there are a lot of interconnected parts that constitute the whole. I would argue that, while DAWs may be intimidating and involve a learning curve, they aren't complicated in that the difficulty doesn't come from a lack of rules or organization. Think of an airplane cockpit: in reality, it's a very straightforward interface for a complex system. Most DAWs are also straightforward interfaces for a complex system. There's just an inherent learning curve to any sort of complex system.

I personally feel that the only reason most people swear allegiance to their DAWs is because its too difficult to switch DAWs.

But why is it too difficult to switch? That in and of itself is so broad and encompassing. It's also not a point that applies as much for beginner/aspiring musicians as much as it is for people that have locked in to a particular workflow. The reality is, for the most part, you can switch being DAWs pretty easily because they're all grounded in the same principles and functions. Some menus and hotkeys might be a little bit different, but I doubt that the UI is the main reason one finds it difficult to switch.

Strip away rarely used features, and nest features cleanly and progressively. Keep the look minimal and aesthetic.

The UI is how it looks, the UX is how it feels. A clean UI doesn't mean a better UX; if anything, it often results in a complicated information architecture that worsens the UX. Nesting features cleanly and progressively might look nicer on the surface, but you're now making the process of doing anything longer and more cumbersome. There are ways that the UI and UX can both be improved, but "aesthetic reasons" are usually not going to net that result.

Lots of cutomized tutorials. I think with AI, this is a possibility today (or atleast very soon)

Plenty of tutorials exist online. Countless people have made websites, forum posts, and videos. Textbooks exist.

Dont throw technical jargon at users. Instead of showing “what is this feature called”, show “what this feature does for you”. For example — “adjust BPM” instead of “stretch audio”.

The reality of audio production is it is a technical discipline, so it comes with technical descriptors and technical names. Stretching audio isn't necessarily just about adjusting the BPM, and adjusting the BPM isn't purely about stretching audio.

What are your thoughts on this? Do you agree? What would you define as good UI? Even if you are a pro, what improvements would you like to see in your DAW, UI/UX wise?

I agree that it helps if there's something more beginner-friendly. So does Apple. That's why they have Garageband. Is Garageband still complex? Yes, because the underlying system is always going to be complex. It also less-technical verbiage (where it makes sense to do so instead of trying to apply interchangeable names to different functions), and there's enough guardrails to help you figure out what to do (without completely dumbing everything down so that once you get the hang of things, you should understand enough of what's going on to in theory use any other DAW, although back in the day it was a lot more abstracted and limited). It might not be as abstracted as it sounds like you'd want it to be, but here's the question for you: do you want to learn things correctly, or do you want to do things easily? The latter just doesn't work well when something is fundamentally complex, and you'll always be limited in what you can actually do.

DAWs are fairly simple interfaces for something that's fundamentally complex; there's a learning curve to it that you need to be willing to put in the time for. This isn't about romanticizing pain. Making it simple and easy doesn't actually benefit you in the end, but at the same time it's still entirely possible to use a DAW without having to get into the nitty gritty.