Software lag isn't unique to touchscreens. Software lag is always a terrible thing, and developers who de-prioritize performance should be ashamed, but that is true regardless of what input is used.
Now ask anyone with a touch screen in their car what their error rate on that thing is. Even the really good ones are pretty bad.
Touchscreens don't work quite as well for this. Even if it allows for input queuing, you often still need the previous screen to finish drawing to have a frame-of-reference for your presses. Even the slightest delay turns into an annoyance, and when it involves some kind of drag-scrolling a 50ms delay already becomes unbearable.