I think they're important, for sure, but not a show stopper for me if they aren't top notch. The same goes with sound for instance. Something that we all want (at least most of us) is inmersion, you need good physics, realistic FFB, but also graphics and sound. I think that a good simulator has to be well balanced among those factors, otherwise, you either don't feel "connected" to the car if physics and FFB aren't good, or kind of bored if visuals and sound don't attract you (obviously this is a matter of personal taste... but this is what happens to me).
I sometimes find rF2 more visually appealing than assetto corsa just for the night-day transitions and other details like realroad. I can spend hours doing hotlapping in both AC and rF2 but the fact that light is actually changing in the latter just adds that tad of realism that makes me come back to the game, what I mean is that realism doesn't always rely on highly detailed graphics.
I sometimes find rF2 more visually appealing than assetto corsa just for the night-day transitions and other details like realroad. I can spend hours doing hotlapping in both AC and rF2 but the fact that light is actually changing in the latter just adds that tad of realism that makes me come back to the game, what I mean is that realism doesn't always rely on highly detailed graphics.