I’ve seen a lot of complaints on armor cores and actually like the idea of the armor core system to a point. The biggest fix would be to make visors and coatings not bound by cores. But the best thing to do would be a rare core that supports all armor, it would need to be earned, take time to earn, and most importantly cant buy it. Maybe make it as hard to get as the haunted helmet from reach like maxing your level (if they add levels). I think it would be the ultimate reward.
I would agree with some of what you say but I believe all armor should be allowed to be used by any core. Bots already prove that it is able to be done. Not only that, but the meshing for helmet attachments also seem to be modular, allowing you to take an attachment which seems like it should only work with 1 helmet and use it on any other in the game. The code for this is already in the game.