Seems like it would be useful in an environment like a gun range where you aren't relying on it for safety.
A) as another poster noted, the whole reason you go to a gun range is to get more better at shooting the guns you have, so that if you need to (or want to) use them for real later - either quickly like self defense, or more methodically like hunting - you know how well you can aim with them, what realistic distances are, how much kick to absorb or correct for...
B) Which leads us to a fingerprint scanner being a disaster in a crisis situation like a home invasion, you don't have the time for that nor want to rely that a gun you might have not touched for a while still has power enough to enable the fingerprint scanner. Similarily if you go hunting, it would REALLY REALLY SUCK to travel for hours to find out your fingerprint friend has no power or just decides that environmental conditions mean your fingers are now invalid.
So said fingerprint scanner gun would never be a gun you would use in real life, making it pointless to shoot at the range,
You mention hunting - is it really a quick draw sport where if the reader takes an extra few seconds to recognize you, it's a critical failure? Sure maybe you might have to pick a new target, but I wouldn't call it critical.
And what about shooting for FUN? You know, recreation? I never plan on having a gun at home, or using it for self-defense (the stats are against me anyhow - as in guns at home typically end up killing the owners more often than the intruders).
This is what's wrong with gun culture in America. Everyone seems to assume the only purpose of a gun is self-defense. True, you can use guns in this manner, and guns are often used in this manner (see: military). But I'm willing to bet they're used far more for both recreation and hunting. Everyone seems to believe that a gun is purely to kill someone, and no one can seem to wrap their heads around the idea that there are plenty of people who don't want to do that at all, or who are smart enough to realize that self-defense is probably the worst possible use for most people.
Hell, even arming the populace makes it a more dangerous world - wasn't there a sniper at the University of Texas Austin campus back in the 60s? Everyone raced home and got their rifles, and the end result is there were more deaths from friendly fire than deaths caused by the sniper. In fact, a police officer who took down the sniper was nearly taken down himself from one such equipped student.
And why do you want to go to a gun range and fire off a gun? Why not? Why do people run for fun (they're not planning on doing a marathon)? Why do people race cars on tracks (they're not going to join the F1 or other race league)? Or play instruments, or do dozens of other activities, by the end of which they can be better than a professional.
Maybe it's time to drop the self-delusion and just admit they're fun to use and mastering anything doesn't have to be for any end goal, other than the challenge of mastering it.