In the realm of land battles I think the simple UI change has really helped with conceptualizing battles. But I disagree with almost everything you've put forward.

I don't think stellaris should be the tactical game you're suggesting it should be. Grand strategy is the name of the game. Micromanaging armies once afield is not your responsibility. It is literally what your generals are for. Just like with fleets, you may choose when they engage the enemy, but no decisions on how to prosecute that fight are left up you. That is why you have admirals. The main problem I have with it is the assumption that we (modern humans) have any idea how the wars of the far future will be fought. I personally love the ambiguity of the current system. It allows the player to conceive of warfare in however complex or simplistic he wants it to be.

However I am a fan of anti-orbital weapon systems as buildings, manned by defensive armies. Possibly long ranged weapons that could participate in the initial fleet battle, medium ranged weapons that that could engage targets near the planet's orbit, and short ranged weapons that could engage armies as they are deploying to the planet.

I would like to see a move to make army management similar to naval management. An army builder and an army manager. Managing armies by how they're equipped and trained, like creating classes of ships, might be close to the types of troops you suggested. Additionally armies like fleets to make them and your generals a bit easier to manage.