Depends how the traffic lights are removed. For instance, I only use the standalone traffic lights toggle mod, this does not add any way to prioritize roads at intersections, and does not add the stop sign functionality, hence, it looks like an intersection from a poor country where everyone is pretty much rushing into the intersection. It does not help at all without implementing stop signs or road prioritization. Because you now have all vehicles pushing into the intersection from every direction, stopping themselves constantly as their destination collides (left turn vs straight), and they trickle at like 1 or 2 cars on a really busy intersection. I think traffic manager has road priorities, so that's a plus, but i havent used it.

I have noticed that cars flow more fluently when there are no traffic lights and no priorities, so I am not sure about your findings. Yes, it looks bad but it appears to have zero negative gameplay impact.