These three things seem like the biggest topics on the forum, sometimes, and people tend to offer a lot of solutions. Ultimately, I think the only real solutions to these issues are ones that expand on the mechanics in a simple way and ones that make them more rewarding than they currently are (when used properly).
Doomstacks take away complexity from the game, so the player needs to be encouraged to split up the fleet, not discouraged from doomstacking. Consideration needs to be made for preventing stacks of multiple fleets, as well. The cost of maintaining a gigantic fleet needs to be higher than that for multiple smaller fleets (preferably in different systems). There needs to be a reward for operating in multiple systems as well, like increased chance to evade. There should be more lucrative targets to attack/defend during wartime, somewhere below frontier outposts but above "+1 resource" (and, on that note, frontier outposts honestly need to be better equipped for defense).
Armies ought to be customized and built in a way similar to naval ships. That's honestly the only way anybody will think to make use of the attachments. Armies should be specialized in more ways than "moral, health, damage." I do think there should be some sort of advantage/disadvantage system, possibly revolving around psionics, robots, and genetics. Furthermore, ground combat should involve a simple minigame; something with a basic level of strategy requiring us to think about our approach without having to pour thought into it. I've seen some suggestions but they've all been a bit complex.
There's a quarantine thread for sectors, so all I'll say is that sectors should be more rewarding than they are now. Putting a planet into a sector, especially a specialized one, should benefit the player with resource buffs. Furthermore, "core world" planets usually consist of the home world and distant planets having groundwork infrastructure being built. That's pretty lame. Some sort of "core worlds" sector would not run amiss; a thing to put our closest planets into that we can still control but doesn't count towards our total number of planets in sectors.
Doomstacks take away complexity from the game, so the player needs to be encouraged to split up the fleet, not discouraged from doomstacking. Consideration needs to be made for preventing stacks of multiple fleets, as well. The cost of maintaining a gigantic fleet needs to be higher than that for multiple smaller fleets (preferably in different systems). There needs to be a reward for operating in multiple systems as well, like increased chance to evade. There should be more lucrative targets to attack/defend during wartime, somewhere below frontier outposts but above "+1 resource" (and, on that note, frontier outposts honestly need to be better equipped for defense).
Armies ought to be customized and built in a way similar to naval ships. That's honestly the only way anybody will think to make use of the attachments. Armies should be specialized in more ways than "moral, health, damage." I do think there should be some sort of advantage/disadvantage system, possibly revolving around psionics, robots, and genetics. Furthermore, ground combat should involve a simple minigame; something with a basic level of strategy requiring us to think about our approach without having to pour thought into it. I've seen some suggestions but they've all been a bit complex.
There's a quarantine thread for sectors, so all I'll say is that sectors should be more rewarding than they are now. Putting a planet into a sector, especially a specialized one, should benefit the player with resource buffs. Furthermore, "core world" planets usually consist of the home world and distant planets having groundwork infrastructure being built. That's pretty lame. Some sort of "core worlds" sector would not run amiss; a thing to put our closest planets into that we can still control but doesn't count towards our total number of planets in sectors.