[ As I have told before, the world is very deadly even though very few enemies use such abilities.
The biggest problem would be the wild hunt enemies. Each of them does try to paralyse the whole group every round.
Freedom of movement is your friend. And is not a hard spell to obtain in scrolls or for your cleric.
I think PK was quite unintuitive for both Pathfinder players and those new to the system. I remember there were a lot of complaints (when the game came out, later I didn't follow the forums anymore) from Pathfinder players, because the devs have elevated stats on enemies and those familiar with the system didn't expect the stat bloat. So they were struggling with combat. Meanwhile I didn't know about Pathfinder before playing that game, so I wouldn't know what stats & abilities an enemy was supposed to have anyway. On the other hand I've found building characters difficult, because the many bugs and also misleading tooltips made character creation a guesswork.
(...)
like no flying in a 2D game
The devs made earlier fights far easier, due people crying. Kingmaker was the unique game which I ever pre ordered and my first run lasted till Pitax due a infamous bug. A lot of harder encounters(most of then optional) got far easier. And most complains about the combat are nonsensical like "I can't use a sword against an insect swarm, I need to use torches or bombs".
As for flying, Solasta did implemented flying and M&M VI, a 1998 game had flight but kingmaker could at least made flying creatures immune to ground based effects/spells.
But about the ruleset, the best ruleset depends a lot on the game which you wanna to play. For eg, Dark Sun on 4e or 5e would't be the same as Dark Sun on 2e. Dark Sun is a harsh dying world and we need a ruleset that reinforces it. Just like the realms of dread on 2e and on 5e are completely different experiences. Ops, there aren't realms of dread on 5e, only Barovia.
That said, there are so many spells and effects which Larian can't get feedback with lv cap = 4; and 5e is far more low level friendly compared to 2e, paladins only start to get their spells as lv 9 on 2e. This and the fact that modern game market is extremely obsessed with balance, means that the chances of high level gameplay is near zero.
And 5e also suffers from the "oblivion effect"(for those who don't know, oblivion is infamous by having enemies soaking hundreds hits at higher level due hp growing far more than damage), where the hp growth is extremely greater than the damage growth. For eg, on 2e a wizard at lv 5 will deal 5d6 damage with fireball. At lv 10, 10d6, each new level adds d6 to most damaging spells, meanwhile his hp grows by +d4 until lv 9. After it, grows only +1 hp per level and the con mod was far smaller. So higher levels maintain his lethality. Meanwhile, on 5e a wizard gain d6 + CON MOD hp each lv up and spells gain no damage. In fact, a fireball deals 8d6 damage on 5e as a 3rd tier spell. While a freezing sphere deals 10d6 damage. For 3rd tier spell to 6th tier spell, the damage growth with the hypotetical evokation spell is miserably 2d6. Meanwhile, the wizard from lv 5 to 11 gains 6 * d6 + CON MOD. Even with 0 con mod, the hp gain is 3x greater than the damage gain.
And monsters grow up on hp per CR in a much exponentially way. High level encounters on 5e can take dozens of rounds.
Many DM's also complain that is hard to challenge a party on higher levels. Because nothing is a threat to theyr near infinite hp pool. I love high level but for 5e, we should focus more on mid level.
