I humbly request you to please change the name of this thread to 'Stellaris is a great concept, and a nearly great game.'
There are just too many posts at the moment seeming to infer that stellaris is terrible. And it's not. And we don't want to scare away new players. There are definitely things we would like to see improved or fixed. Stellaris offers great roleplay and immersion, but many of us with 2k+ hours in it may be too jaded to still see it that way.
Having said that, my contribution to this thread ....
- I would love to see a UI/UX rework to make the game more accessible and less micro. It's almost as if the original design intent was to achieve fake depth through convoluted UI. I put this first, because it is the area most likely to scare away new players. This includes popups, notifications, message histories, outliner, map overlays, THE PLANET SCREEN, and fleet and army managers.
- The species design can be a little clearer about roles of ethics, government, civics, traits to distinguish between elements that describe your species and things that describe how you address those challenges. E.g. ethics and traits are about what my species expect or need, and government and civics is about how I address those needs. Same with policies (player intent) and edicts (empire control).
- We are for now stuck with hyperlane. I would have preferred warp. But it is what it is.
- Finally, the big elephant. AI and automation. The AI needs a significant overhaul in the area of economics and military behavior. Too many disjointed systems that don't contribute to an overall plan. I put this last, because it is the area that only really hits you when you are an experienced player. This extends to having a collection of 'governors' for sector/planet automation to take micro away from the player. This almost worked with the last big update in this area, but there are some fixes needed (building upgrades and rare resources).
For the rest, it is small in the scale of things ... ship balancing, technologies, job assignments, resettlement, logistics and various mechanical tweaks to encourage advanced strategic play.