I love navy, and have always thought it was a bit underdeveloped in this game. I have been studying naval history for game development reasons for another project, but as for games I don't see a lot out there similar enough to FAF to really get a good metric for what people find fun. I really like the macro aspect of SC, that's what brought me to it, and others above have mentioned not just random micro but micro that's actually fun and has a use. One quote I like for game dev is "A game is a series of meaningful decisions" from Sid Meier. So how do we add options to the t3 navy that let the player make meaningful decisions, and if they have the APM, boost their fleet effectiveness?
We could add toggle-able abilities. I'm unsure what would be viable, but toggling your big ships from direct fire to plunging fire, or a tight vs wide spread, seems like it would be useful. Something like an overcharge could be done too. A hard hitting shot that costs energy or mass, with a cooldown, etc. And the right click 'auto use' feature. Perhaps it can do HP damage to the ship per use or something?
I think every ship should start with HP regen. Ships have damage control and I think for big ships this could be expanded upon. A fast repair mode, (or an ACU style upgrade that only repairs HP damage), that disables the ships guns and movement, and makes it extra vulnerable to torpedoes (IE, adding late game raiding targets for subs). Could be interesting. I think this would pair well with expanding on battleship veterancy. Adding other benefits through the ranks to incentivize keeping your capital ships alive, and tending to them.
If I can find time I will try to mod this in to test it.