It is my understanding that the issue people have with Civ Switching is more thematic and less mechanical, so reiterating the mechanical advantages of it don't really address the root disagreement. I might be wrong, but that's the read I've gotten.
I agree that it (conceptually) has great mechanical advantages, but it's also such a dramatic change that there will inevitably be some unintentional, new mechanical problems introduced by it. On the whole I think the benefits will vastly outweigh those new problems, but I think we should all be expecting a few bumps on the road with this new system. And if you already don't care for the change fundamentally due to thematic reasons, those bumps might feel much larger than they do to others.