[Since you appear to be trying to engage me in a sincere discussion, I will reciprocate.] I agree with your point that the player is going to be trying to manage not only the fireball-casting wizard but also at least three other characters all at the same time. And as such, this could be overwhelming and difficult for a person to manage. But here's the key point for me in all of this, including what I said earlier about the whole fireball casting business. You seem to be (I'm guessing; you can tell me yes or no) looking for everything working out optimally, perhaps even perfectly, across all your party members' actions. The fireball gets cast perfectly. The wall of force you wanted to place gets placed perfectly. Every one of your party members does their respective actions in the round perfectly and optimally. But I don't want this to be how combat works for me. I want combat to be sub-optimal and imperfect. I want there to be screw-ups and mess-ups and things not working out exactly as I had planned or hoped for. I believe this is how combat *should* be, especially in an RPG.
So maybe (Again, I don't know. I don't have data. I am making an educated guess ...) the difference between fans of TB combat and RTwP combat is that TB fans love making some sort of "perfect" plan for how combat is going to unfold across the whole encounter, or at least across each round in the encounter, and then they want to be able to carry out that plan in an optimal way (fireball gets cast perfectly to hit maximum number of enemies and no allies, for example), whereas RTwP fans don't care about having a perfect plan for winning the encounter and their fun comes precisely from winging it. I've heard very often TB fans describing RTwP combat as being "chaotic" or "confusing" or "messy." They are correct about this. The difference, I think, is that we RTwP fans like it and want it to be chaotic and confusing and messy, whereas TB fans don't.
If you think that turn-based combat means that everything you do goes perfectly every single time and nothing ever goes wrong, you clearly have little to no experience playing turn-based games. Turn-based is not a magic guarantee of perfection. Things go wrong all the time. You make a move that isn't as effective as you hoped, or is sub-optimal, or the enemy does something that you hadn't expected. Things go wrong all the time. There's no such thing as a perfect plan where everything goes right.
Maybe someone will make a mod so that when you give a character an order, there's a 25% chance than they instead perform a completely different action than what you told them to do, and a 10% chance that they'll perform the same action, but on a different target than you told them. That's messy and chaotic, but does that sound like it would be fun?