My biggest complaint: RNG Drops are bad enough - especially with the abysmal drop chances we currently have. RNG stats as a core part of loot progression and the loot end-goal is outright bad. Normalize gear stats and restrict RNG variance to a few pieces of gear at the very top.
As it stands, the overwhelming majority of non Mk III gear is simply not worth using, not just because of the terrible resource economy (thank you for at least acknowledging that, though I was hoping after Syndicates, Plains, Fortuna, Vox Solaris, etc. you all at DE would have gotten better at that), but also because of the RNG factor. It's just not worth investing in anything but the highest end gear, since the stat variance is so damn high. Furthermore, non Mk III drops are pointless as soon as clans have finished researching their standard non RNG stat gear.
Somewhat related: the changes to Archwing movement are really good. However, even with those changes, collecting loot dropped in space is a PAIN. It's good that it's shared with the team, but it's still not worth going back to loot that was dropped out of the way several kilometers back, because you keep moving forward during a mission, and having to double back is tedious and un-fun. Please make all space drops instantly pick up on drop.
Also: Part of the reason why Amesha is by far the most used Archwing is that the energy economy for Archwing is attrocious. Especially early on, players are reliant on their Archwings, because beginner Railjacks are about as resilient and dangerous as Kavat-droppings (read: I could do more with an uncatalyzed Frost and a Burston Prime). With the nerfs to Archwing damage, Archwing abilities are all the more important. And the only Archwing able to spam all its abilities is the Amesha, because its the only Archwing with a reliable way of generating its own energy and keeping the Railjack alive.
Just how Energy Siphon should be given to all new Warframe players for free, Archwings need to have some other means besides Kinetic Diversion to generate energy (I'm MR 27 and have never seen anyone with that mod, let alone myself).
( for reference: https://warframe.fandom.com/wiki/Kinetic_Diversion )