What? How do you reach this conclusion?
In any case... I agree with you, but for different reasons. "Darkness detectors" is kind of a weak function, considering the innumerable other ways of determining darkness without relying upon bats, which frankly don't spawn all that often. That said, I do like ambient mobs such as bats that don't necessarily serve a purpose but are in place mainly for flavor, so I don't see some burgeoning need to give bats a legitimate function. Honestly, I'd like more creatures like that (Tropical Fish kind of fill this same role, only dropping the Clownfish which is pretty low value)
I propose to make their purpose utility rather than drops - they could disorient mobs, decreasing their player detection times and radius.
Why? Bats already have a clear function, they're darkness detectors. You haven't given any details at all, and at this point I'm honestly suspicious that your post is even about bats at all. Convince me otherwise.
When? Sometime within the 1.17 update cycle. Yes, this would in fact be a sensible point to update bats and knowing Mojang they probably even have something up their sleeve for bats already. Maybe it's a uniquely-Mojang inspiration, or perhaps it's an adaptation of any of a number of long-standing bat-related suggestions made over the years. However, 1.17 snapshots have already started to come out so unless Mojang is keeping some sort of bat-upgrade under wraps until later in the cycle it's likely far too late for even the most perfect of bat suggestion to be implemented.
How? Psst, this is where you respond...
Darkness detector seems very inconsistent and poor function.
Grunting, rattling and screeching of hostile mobs already does that.
Honestly, I didn't even realize it's an utility of a bat so now, so don't speak about clear.
I agree with OP, though he more described a problem for a brainstorm than direct suggestion.
I doubt that. 2 Reasons.
First: In dark spaces spawn most of the hostile mobs, wich also drop items, not just exp.
2nd: I haven't seen a good / efficient phantom farm so far and they do aggro you, where bats just randomly fly around.
Well there might be good phantom farms but google doesn't tell me.
It would be fun to see a redstone machine killing large numbers of flying mobs for a change.
Right now i would make bats dropp any item. (like rabbits foot, just the bat equivalent)
They are so hard to hit, if you want to, exp would not be a reward.
Or make them entitys that can not be hit. That way they wouldn't be nasty obstacles in dangerous situations.
And i would absolutly apriciate that. Cause thats the only reason i am hating bats.
I think Mojang won't be so fond of making endangered species worth hunting.
I propose make them utilitarian instead, disorienting other mobs and decreasing their awareness, resulting in shorter player detection radius.