Hey! Thanks for reaching out, and no worries. I didn't mean to come across confrontational at, I tend to just state my thoughts/opinions very directly. At the end of the day, I'm just some guy, no need to take anything I say as gospel! that said, I'll respond to your questions in order.

I think my main problem with the menus, while the AC influence is apparent, it does not go far enough. In nearly every AC game, you are able to toggle between several views at once, which will show you how the various stats are affected on a per part basis, overall basis, and comparative basis. I think the problem is that, in the game as-is, I feel like I'm not seeing enough information to make meaningful decisions. I can see how a part compares to what I currently have equipped, but I cannot see how that affects the overall stats. If this feature is already in the game and I missed it, I suppose there's an argument that it should be more obviously accessible. I feel it's unfair to necessarily complain about the aesthetic of the UI, but it is ugly in my opinion as well. Reading it just doesn't feel good? I'm sorry that's not particularly helpful... I don't know how to properly articulate it, but I feel like my eyes glaze over trying to read it?

As for the boosters, perhaps just reducing the flame effect visually and lowering the SFX to like 30% of its volume when stationary? I'm not sure how you came across the sound effect or if you made it yourself, but it may be worth looking into injecting brown noise into the mix to make it more pleasant to the ear. 
I think it's also worth mentioning that sound effects will play over the top of each other and get deafeningly loud at times; I'm no expert but I think this is a relatively easy problem to solve? I feel like I've seen someone implementing a fairly easy solution in a devlog somewhere? Again, sorry if that's not entirely helpful.

I see your point that the shield taking a slot could be a downside, but in my experience, it's so incredibly good that I feel it's an obvious "best in slot" when it's an option. I'd be willing to guess that new players avoid it because in most other games the shield is far weaker and more "balanced" in a way. I avoided the shield in multiple runs, until it happened to be the first weapon I obtained in a run, where I quickly realized how good it was. It's definitely something that needs further adjustment and experimentation.

Yeah, melee is rough. I will say, the "kick" is incredibly satisfying, so much so that I was completely baffled and disappointed with laser blades. I can definitely see why you chose what you did, but I think the 'skill floor' is way too high to make them remotely viable. I can't think of a scenario where I'd use the laser blade over a kick. 
I hate to repeat myself so much, but in every Armored Core game there is a lunge of some kind associated with melee weapons. I don't think you should necessarily think of this as something that removes player agency or deters higher skilled play, but rather something like recoil on a gun. It will convey more momentum and feel more powerful. Perhaps, you could make it so the longer, bigger, more powerful blades make you lunge less, and smaller blades lunge more? to compensate for their stats? 

For the environment, I think it's a combination of the textures being not only cluttered but also the high contrast within the textures. If the environment textures had subtler details, I think that would alleviate a lot, because right now it's almost like looking at a zebra pattern due to the level of contrast between details. 
I think a radar or maybe even just a compass (maybe a toggle option between the two) is a good idea for sure, in terms of navigation. 
I think something that may help, while being subtle, is to give the enemies a color shift/tint that is complimentary to the environment (i.e. blue-shifted environment has yellow-shifted enemies). I think this could be implemented very subtly while still helping a great deal. It'll also help add variety if each level/stage is visually different, even if it's just the color palette. 
Speaking of color, I think implementing the option to type-in or copy/paste a hex code or RGB values would be very nice QoL for Mech customization.

To address this, I'll acknowledge I was a bit mean here in my initial feedback. I'll apologize if that came off intense, but it came from a place of wanting you to make the best game possible. I'll say again, if it didn't come across that way, I apologize. That said, I think the main thing about the game that feels like RoR is the random enemy crawl, and the aimlessness of the game in general. I think you're on the right track already, but progression should feel more impactful. 
I got a "rare" version of a missile pod I was already using, and I didn't notice a meaningful difference other than it fired more missiles at once. I had a similar experience with a shield, where a normal shield (perhaps due to the confusing stats) appeared to have better stats than the 'upgraded' ones that I found. 
I feel enemies should have some degree (or an illusion of such) of autonomy other than walking straight towards the players. Even if they just randomly walk in a strafing pattern or something; if this is already implemented, then maybe it should be exaggerated more? as I didn't notice. I think verticality should be played around with more as well. It felt like most enemies just walked towards me on the ground, and the flying enemies were the only ones that made me really look up or move around. Perhaps something as simple as a jumping enemy?  
As for the "structure," I don't think it's fundamentally flawed per se, it just needs refinement of some kind. A goal to work towards other than just loot. If there were, say, permanent upgrades similar to Vampire Survivors like "Earn double currency" or "retain one part for the next run" that were signposted to the player and made the game experience more compelling. Like, "Oh, if I make it through three levels, I earn double currency on the first three levels in future runs." Some people find it controversial, but almost every successful roguelite has an underlying permanent progression system that can allow even an unskilled player to eventually power scale themselves through the game with enough determination.  

I am also excited for the "core-like" renaissance that is almost certainly impending. I found your devlogs on YouTube several months ago now, so to be clear I am a fan, and I have been following the project. I apologize if the things I said/say are not entirely clear, but appreciate you engaging with me none-the-less! I'm 31 years old, and I played a lot of the Armored Core games back at release. I was actually a FromSoft fan *because* of Armored Core, and I was a bit resentful during the Souls-like era due to the dry-spell. AC6 was a truly incredible game, not only in its own right, but the potential for getting new eyes on the series. I am very excited for your project and seeing where it goes/becomes. Good luck, and thanks again!