Casters are OP because in RTWP half of the Martials options dont even exist. Its a fundamental flaw with DnD. And the only edition that fixed this flaw, 4e, was universally hated by purists and thats why WOTC now locks any usefull maneuvers for martials behind the Battlemaster subclass for fighters.
RTWP makes the whole thing worse by making movement far too safe, thus making martial battlefield controll even harder to achieve.

i talked about the way it works in icewind Dale because thats the last RTWP game i played.
NWN 2 has a very different engine with its own problems stacked on top.
I also dont think RTWP supports multiplayer better, id id play NWN2 Storm of Zehir in multiplayer quite a bit and the result is... having to pause a lot for both players.
Having your actions suddenly interrupted because the other player wanted to adjust one of his characters, which especialy in NWN2 can lead to a lot of dumb stuff like your character forgetting what he was supposed to do.

meanwhile OS2s multiplayer combat works extremley well.
And if you dont like waiting, several games have figure dout how to do simultanious turns which also does away with that problem.

You are also exactly wrong about casters. in Turn based, you mut commit to your movement as you rightfully point out. This means you must predict what your enemy is going to do on his turn.
In RTWP; you can change the direction of your move at any point and immediatly react. Thus its less tactical as there are less risks to be taken.

Iuris Tantum
Agreed on reactions, theres more than just that, i realy wanna see how RTWP pulls off stuff like grappling, but no system so far has even attmepted that.

why dont you explain what makes the combat system good.
Because in my opinion, you just stop paying attention to 5/6 fights. Oh look its goblins again, lets just autoattack them to death. or lets just cast fireball and thats that.
From what ive heard from people that enjoy RTWP, the parts about RTWP they actually like, as in, the planning ahead, the thinking what each character is going to do.
The identifying of enemy casters and what they are going to do.
All of that exists in turn based systems. But without the tedium of trash monsters.