Arcade racers are just a bit more than the driving physics, I doubt in racing sims you have to care about dodging oncoming traffic. Just because one component is simpler, or in many cases just unrealistic doesnt mean that the game is simpler or less depending on fast responses.Personally I think it's the opposite. I think arcade racers are more predictable because the physics are very simple. With sims, I don't think it's just about memorizing tracks and brake points etc. When you're racing high powered RWD cars on a track like Nurburgring (especially in rain), responsiveness and reaction times are very important. Getting a good feel for the traction of your tires is key in getting good lap times (ie when you're gripping and when you're not, when you should give it gas and how much, or when to let off etc.). And every car is different in how they handle, and weather effects and what tires you use (as well as the condition they're in) greatly change things as well. Game makers seem to agree since almost all racing sims are 60fps and almost all arcade racer are 30fps.
Why is "realism" a thing anyway? Its not like I learn driving a lamborghini by handling a detached gamepad - sitting in one will give you alot more feedback a screen and speakers can provide (Id rather have a fully simulated damage model and newtonian car pushing anyway). Could aswell just assume that the lamborghini onscreen is driven by someone who can handle the crude basics so I can focus on the Truck coming straight at me while pushing the dune-buggy of the road. Might be that driving around in circles without leaving the road the same way over .. and again.. and again is harder in sims vs arcade racers... the point is that arcade racers just dont stop there. So its easier to drift, you still damn need to know the exact instant you have to drift, brake and do all the fun things that are impossible or despised in real life. And that makes the game alot more complex, usually faster and more dynamic than sims, where you can have an otherwise braindead AI field precomputed perfect laps.