I've got some bases with the nuclear reactor
I mean, it's a sandboxish game and everyone play as he like but whining about 'tedious' stuff like nessesity to drink which can be turned off comlpetely at the start or can be easily neglected after trip to the island on what, 1-2 hour of playing? Which is an actual flaw unlike some stuff you've listed - the mechanic is too simplifyed which doesn't make sense given the fact that it's optional. You just grow food on any, even 1 room base or on Cyclop and that's it. So, as I was saying, whining about that while having multiple bases with nuclear reactor (which yes, is completely fucking redundant and that is another obvious flaw) seem crazy to me. You don't actually need multiple bases in this game by the way.
The combat aspect of the game is fucking terrible.
There's no combat aspect in this game. Well, maybe except for the headcrabs, allright but that's it. You can safely ignore all the fauna and be aware only about the reapers but their danger comes from ability to get you under the textures, that's beyond annoying and cost me 2 hardcore attemts until I memorized their habitat.
Scanner room - kinda reduntant if you learn where each resource comes from via manual scanning. But with HUD chip it might be useful towards the end.
This is stupid. I wasn't whining about needing to drink water, I said the rate at which you need to eat and drink is tedious. It's too gamey. In reality you can go a few days without drinking water and at least a week without eating before you just die. In Subnautica you're in danger of death if you don't drink water for like half a day or something ridiculous like that. I don't want to play the game without eating and drinking because that's part of the game, a huge part, but they pushed the rate at which you need to do these things into tedium. It only really gets better once you get the water system and the hot knife, because then you've got water bottles that have 50 water instead of 20 (as well as all the salt you want to preserve fish) and a can get cooked fish at any time...and I didn't have these within a couple hours of starting.
Multiple bases makes shit easier. I don't want to have to go back and forth between my first base and like to the islands or the entrance to the underground river. Also makes finding shit way easier since I can just scan some to area for whatever or resources and see if there may be some paths around.
You know when you say there's no combat aspect, and then after writing it out you remember there is, it's ok to just go back and delete it? Those crawlers are a combat aspect, and they're all over the islands and the ship. I'd also call the Warpers and Mesmer more direct combat aspects too since they're actively more hostile than the other hostile creatures. I'd even kind of file trying to hit fish with the hot knife so you can cook them quick under "combat," at least an aspect of it, even if you aren't in a fight. Like I said, I didn't mind it being bad in the beginning when enemies seemed more designed to avoid, but then the game starts throwing in more standard enemies.
Inventory - just learn how to manage it, do not pick up everything you see.
This is fucking stupid. Yeah, that's what I do. But it's dumb I have to do that, and I didn't know the inventory system was so stupid when I started. It feels like an inventory system made by someone that never played a game with an inventory system before, and is under the impression they're just figuring shit out themselves. What makes this dumber is the game doesn't let you drop things in a structure, but it will let you do it outside of one. So instead of just throwing some shit on the ground right where you are to move some stuff around quick it makes you run around a bit.