Note: This list is by no means exhaustive, it's mostly things I've seen myself and believe take the highest priority for fixing.
- CLs/CAs have limited roles
Pretty self-explanatory, they lie between DD and BB in terms of min/max stats. DDs are great because they are so fast and small, able to sweep in through blind spots and pin down BBs/CVs quickly, whereas BBs have awesome firepower and hitpoints. CLs and CAs are in the uncomfortable position of having neither speed/small size nor firepower/hitpoints. As a result, they merely support BBs against things that would rush them (which BBs generally have little difficulty taking out anyway, just ask a Moltke/Lord Nelson captain). These need to be given a more definitive role.
2. Gun accuracy scales down aggressively
I didn't bother to buy a Revenge until after I had spent the experience and credits to master both the Lord Nelson and the Dreadnought. Despite giving my crew ample time to train toward the bigger 15" guns, the accuracy on the Revenge was, in a word, terrible. Not just at max range, but at ranges the 12" guns can almost block-shot. As far as I'm aware, this is the case for the T6+ BBs of every nation. I would not mind BB damage taking a hit if it meant I could count on hitting something, because without a fully-skilled accuracy crew (and probably morale boosting too) I won't get the accuracy I need to actually be effective.
3. SS Oxygen scales up aggressively
The opposite of the BB problem, SS have a lot to gain from a fully-skilled crew - too much, in my opinion. It only took me about three hours to skill up a US crew to have two minutes of dive; if I recall correctly, in NF1, that was the high-end dive time. SS have a lot of weaknesses, but they're pretty much moot if I can swing in and out of fleet formations without surfacing in range of guns.
4. Less Mines, More Depth Charges
One of the few things CLs do effectively is sub hunt, or they can if they have Depth Charges. Instead they have mines, which more frequently kill allies than enemies (to this day I have only ever run into friendly mines). In lieu of DCs, and perhaps to address complaint #1, we could bring back the depth charge launchers from NF1. I think they were called Hedgehogs? Those were pretty badass.
5. Fix Armor
I know what you're saying, another sub nerf? But BBs generally don't fit Bulge; it doesn't get nearly as much mileage as deck or belt (a single T5 Deck or Belt can absorb an entire T4/T5 BB salvo, whereas T5 Bulge absorbs a single torpedo). Current armor mechanics also appear to favor smaller BBs, since the amount of armor gained is not proportional to the tier or max DP of the ship (a T4 BB gains as much Deck armor as a T11). I recommend making armor proportional to either the ship tier, hit box, or max DP, and overall reducing Deck/Belt armor amounts to bring them more in line with Bulge.
6. Matchmaking - ship distribution
Biggest problem with matchmaking right now is how it respects Tiers rather than Classes. Being that T9 BBs are currently in a very bad place where T9 CVs aren't, and T5 BBs are in a very good place where T5 CVs aren't, you tend to end up in battles where one side has a ton of T5 BBs/T9 CVs and the other has a ton of T9 BBs/T5 CVs. Guess which side wins? Maybe the one with fighter coverage everywhere and BBs that wreck at short range? Yep. While the intention is good - there should be some variety in matchmaking beyond "6 BBs, 2 CVs, 10 everything else per side" - there needn't be so much variety that one side is dominated by the brutal state of balance. It's also annoying to end up with too many CVs and too few BBs, so there need to be a cap in place to ensure both sides get a minimum number of BBs.
7. Matchmaking - platoons
Tons of threads have been made about this, and I'll repeat what they've said: What's the point of being in a Fleet if I can't get into games with them? We do the whole Teamspeak countdown thing and I still end up in a different game than my Fleetmates.
8. Reward performance/punish power-grind
Right now there's two groups of people: One group is genuinely dedicated to seeing their team win, the other is dedicated to getting exp and credits as fast as possible. Unfortunately these groups are mutually exclusive. I've made 4k experience with no kills and minimal contribution, and I've made 1.4k experience with 175k contribution and 4 kills. The difference? We lost the second game. I have no idea what the exp/credit formula is, but we've also got a huge problem with people staying in games for only three minutes before leaving, giving them about 90% of the exp/credits they would get had they stayed in game and lost/drawn. This is absurd. If you leave a game early, you should get nothing.
Please feel free to add/comment.