There's three minor benefits. The first which is what i used to get the most complaints about when I used to use a more fixed exposure more like the Natural Graphics Mod, which is that when your driving towards the sun on clear weathers people used to complain about the brightness being too much and you couldn't see a thing due to the windscreen reflections etc. Having auto exposure drops the exposure down as far as it can go when driving directly towards the sun and so it makes it easier to see what your doing.Can you explain please what are the benefits of auto exposure vs the fixed exposure with weathers adjusted to that fixed exposure?
The second is very closely related because when you are in the shadows where it's very dark you want to be able to see some detail and once again people had issues with losing in car detail when it was dark. Having the auto exposure allows for this.
Lastly, if we're trying to replicate what our eyes do in reality, your pupils change size to allow more light in or decrease it just like the auto exposure does. Therefore having this effect adds to the realism a little bit.
You could potentially set a fixed exposure and then drop the contrast down so you can see all the detail all the time but then for me personally it looks incredibly flat and bland and that's just not the look i'm going for as I dont think reality looks that way...
On the plus side if it's not for you, due to the way i've made the weathers around the filter you can adjust the exposure setting which will then force the exposure to stay put depending on where you want it to stay...