Turn based combat is a better system and i dont think there is even an argument of the contrary to be made. RTWP is a terrible system that leads to Basic attacks following a turn based models while spells are cast in real time, this leads to an even stronger case of caster supremacy, one of the prime problems with non 4E DnD
This is just patently false. I'll admit that it's been a while since I played BG 1/2 so I can't say if that specific system allowed it, but I know in NWN1 and NWN2 at least you cannot just start casting whenever. You're action is put into a queue (just like any other) and you start it when a new "round" ticks over. So whether or not you can just start casting is a function of the system you build.
And, I believe an argument to the contrary *can* be made. RTWP (or RTWoP) supports Multi-play better. Also, TB makes caster's stronger because Area-affect spells are more effective since the enemies/friends aren't moving when you cast it. You can precisely target. RTWP forces you to be more tactical: Gauging where the enemies are going to go, keeping back your party members from the blast area.