One aspect I haven’t seen in this thread yet is the latency (Edit: I was wrong, it was mentioned by @HXArdito a couple of posts earlier 
), i.e. the delay between triggering an action by pressing a key / button or moving the mouse and the result happening on your screen. Most engines have a lag of at least 3 frames from input to output, and it can go up to 5 frames in some cases. At 30 fps this translates to 0.1 - 0.16 seconds, which feels really laggy when moving the mouse around. Even at 60 fps a small lag is perceptible when moving the mouse quickly.
That’s why competitive gamers aim for much higher framerates. I’m too old to be a competitive gamer and I’m mostly ok with the smoothness of the animation at around 60fps in faster titles, but depending on the lag, higher framerates give a better feeling of immediacy of the reaction to my input - although I usually stop caring around 60fps.
In slower titles such as MSFS, lower framerates are ok in terms of smoothness, but when panning the view with the mouse, it feels really laggy to me when the framerates drop below 40-50ish. As I don’t have to shoot enemies that are trying to kill me, it’s kind of acceptable, but it doesn’t feel good.
Try panning the view with the mouse inside MSFS (usually with the middle mouse button), and move the mouse around quickly. At 30fps you’ll notice the laggy feeling right away, and it isn’t hard to see that this has a negative impact on the precision of aiming at a specific direction.
Edit: This website is useful for comparing the visual smoothness of different framerates: https://www.testufo.com