I just want to share this because its something I've been working on in my free time, and as long as you understand it comes from a place of opinion, but also from a vast wealth of RTS experience from the player side. IE dev's have more data than I can get my grubby little mitts on so take it with a grain of salt.
Lets see if we can't add a bit of complexity to gameplay, while at the same time streamlining overly complex existing pieces as far as the doctrines and elites are concerned. Some of this is going to be brutally honest, but it will be professional and always be with the best interest for the game, and community at heart.
Current elite doctrine set up seems like its been a bit of a pain to balance, essentially players having to pick the better performing ones in MP to make sure they stay as competitive as possible. Having elites and doctrines behind a grind wall can have a tendency to alienate new players, as they won't have the same punch in MP as someone who's been playing and grinding and has access to all of those goodies. I'm guessing the idea for this was to have a reward system that makes the player feel accomplished for their unlocks, but in practice it definitely feels more like a forced chore to stay competitive with everyone else. Video game busy work essentially.
The base building from my own experience feels pretty shallow, with the only real tech options being to push yourself through the tiers, a handful of unit upgrades, and then the force wide upgrades that deal with infantry/vehicle respectively. Forward base positioning is still a tactical choice, and I think its a good mechanic, but the overall system feels really bare bones.
So lets see if I can't at least give you some ideas at killing those 2 birds with 1 stone.
First, lets unlock all the doctrines. It would be one thing if they had parallel buffs, changes to units that had a small buff, but a drawback elsewhere. A good example of this is Solaria's doctrine where you are trading mobility for damage. They aren't all like that though, quite a few are just straight up buffs that make you take them because of how they perform, others don't perform at all. Were going to stick all those doctrines somewhere now that they are all unlocked don't worry.
Where to put those doctrines, well they can shore up how weak the base building feels right now. This fixes a few things in my opinion. Removing doctrines as a choice at the start of the game, all of them. It feels like a game of rock paper scissors at the start, though with the current state of doctrines, its more like rock paper shotgun. I also feel that it telegraphs way to much information to the opponent you are playing, as well as giving you too much info on them. You can see exactly what they are going to try to accomplish in the game unit wise before the match even starts. It's anticlimactic, and makes the matches feel boring to me. Surprises are rare in this game, at least on the ladder. Because of how doctrines currently perform as well, it makes adapting during the match feel clunky. You can't change your doctrine mid match, you picked it before you saw who you were playing, and now you are stuck, and using units without any doctrines makes them feel weak in comparison to those that do have doctrines.
So lets add 3 more buildings for each race, 1 for each tier. They don't need to be super expensive, were only sticking the doctrines into them, and the doctrines are going to have their own requisition prices. Buildings shouldn't be super tanky either considering how I envision counter play. Now this does a few things, cause I see a lot of complaints about early game. In numerous forms actually. Super heavy spam with regular units being an issue with the resource rate bump, doctrines making units in the early game a pain to deal with (Improved WWG in Tier 1, or tireless tacticals and slow death on marines) So with an extra resource sink especially early game you can help balance that heavy unit spam against tech. You don't take the spam play away, you've just now made it punishable by a player choosing to go defensive and tech up. Since now at the start of the game, all units are bare bones, no doctrines, no buffs, and those are now choices you make in game with requisition.