I completely disagree, just because how easy it is to accidentally fire on those damn cops buzzing around without care while you are bounty hunting. If they fix that and you could become wanted only if you did it knowingly, I might agree.
It's pretty easy to avoid. You have all the tools to avoid it. Your scanner shows you where everything is in relation to you. You can look out the canopy to see beams and bullets from a ship flying perpendicular to your path before they intercept your weapons fire. Lastly you can hear where ships are when they're moving towards you.
On top of being aware, there's things you can do to make it harder to hit random ships. You could use your lateral and vertical thrusters to get a better firing solution, where it's easy to see authority ships coming. It's also fairly easy to chase a target away from the swarms of authority ships. Lastly you can use better trigger discipline and only shoot when you're sure you won't hit anything other than your target.
The only change to the bounty system I think would work is something based on standings with the factions.
Neutral and below, immediate bounty. (The cops don't know you or your intentions so there's zero tolerance for accidental fire) the same as now.
Friendly, issue a fine on the first shot, bounty on the second. They at least know you but they don't trust you enough to know it was an accident, thus, the fine first.
Allied, warning on 1st shot, fine on 2nd, bounty on 3rd. You're allied, the faction trusts you enough to give you leeway.
I wouldn't hold my breath for changes though, FDev has said numerous times that elite is a game they're making with their own idea (not ours) of what it is and is not. So unless they personally decide it's too hard to not hit another ship accidentally I'm doubting a lot will be done. If you follow the steps above and pay attention to combat, it's really not hard at all to avoid accidental fire.