Problems I have with Stellaris so far:
1. You know, I wish they got rid of the Pop Grid system and replaced it with something else, maybe something more like Victoria, I dunno.
As it is, most worlds end more or less the same thing. You can't, say, make a world into your Tranton/Coruscant by stuffing it with billions over billions of people, with enough infraestructure and food to sustain it. Which is weird because Precursor civilizations clearly did that in the Stellaris universe.
At some point, if you don't expand, your food production ends up being worth shit because you have no space to grown. What the fuck are those people even doing with all that food that just hits the max limit? "Fuck, our food reached the arbitrary limit, thrown it into the sun". "Wait we could use it feed even more population in our super-techno advanced star-nation that powers itself with Zero-Point Energy" "Shut up and load those crates into the rocket".
It also means stuff like Barbaric Despoilers and Nihilistic Acquisition is immensely pointless, because you can't just take most of your enemy's population and turn your planets into huge slave camps, or sell all those slaves into the galactic slave market.
Historically, population was very rarely limited by space. Fuck, we could cram trillions on Planet Earth if we had enough energy and food.
2. Pirates are retarded. They spawn on one of your border systems, destroy some of your mines for teh lulz, and then go back to their stations to await death.
Honestly, if I handled pirates:
a) Pirates would be a non-state diplomatic factor, akin to Stations and Marauders, but with options more akin to normal states. They have the race of the nation that spawned them, using ethics of dissent groups within (except Pacifist), but their civics attract dissidents from other nations. I'm thinking they would be a far weaker, more unified version of marauders.
b) Pirates "raid" stations in hit-and-run attacks to steal their wealth, avoid armed stations unless they know they can take them and there is no player fleet nearby.
c) Pirates don't have territory or stations, they hit-and-run constantly in any nearby nations.
d) Pirates can be paid off not to raid (space Danegeld), or given "Pirate Haven" territories inside a nation's borders, allowing it to use that nation to as a haven from pursuing forces, while raiding everyone else.
e) Attacks on stations give minerals, energy, food and research to pirates, allowing them to get stronger, build habitats, etc.
d) Eventually Pirates can start vassalizing or even taking over entire nations, if they have enough strength.
3. Too many damn "+%something" civics, governments and traditions. We need less "MOAR NUMBERS" and more things that allow you to do things that bend or change the rules.
4. Related: The Traditions trees are too small, which means your real choice is which ones you will adopt first.
Traditions are meant to be the Ideas from EUIV, right? Ideas in EUIV work because you can't have ALL of them, and National Ideas/Traditions make it so that every nation is unique. They should just expand the Trees deeper, or make more. Oh yeah, we need more and better Ascension Perks, half of them are useless shit lke "Enigmatic Engineering".