I'd prefer a good story over gameplay, but I would prefer real time. Real time makes everything seem more at stake if that makes sense. Turn based is more true to d&d but turn based really just comes across like a mobile game, or something like chess.
When Bioware made the original BG an RTWP title, one of their reasons was that it made for more cinematic and immersive experience.
There were undoubtedly a number of reasons for their decision, but one was probably just hardware progression. As the average PC became more capable, new features could be added that were otherwise impossible. Real time and 3D have now become standard capabilities, but they were not always easy, or even possible, to implement with PC hardware, even at low resolution.