Actually, BG1 used an engine originally intended for RTS so turn based would more than likely have been harder to do at that time.
Why try to bring chess into your arguments? It's a D&D video game and D&D is turn based. It's not like playing chess, it's like playing D&D. BG1/2 had a realtime adaptation of D&D rules, BG3 sticks to turn based. There is no requirement for a sequel to play the same way as the previous titles. I understand RTwP is a unique style of gameplay and fans of that would probably want more, but I'm tired of these demands to rename the game because you aren't getting quite the game you wanted.
Speeding up combat by allowing AI to act simultanously where applicable and adding a fast forward button could make turn based a lot faster, I could see it getting close to a realtime feel if done well. However, full on RTwP would probably not work well with the current design philosophy where combat is highly tactical and turns are generally very meaningful. If they implemented RTwP mode, it would not play that well. If they adjusted the design to fit better into RTwP, turn based combat would not be as good anymore.
