I've long thought that fights might be better and certainly the health of fighters might be better if boxing was only ten rounds. I know how we all loved the old 15 round wars, and we've gotten used to the 12 rounds for championship fights. However, back when I used to spar I often said if I can't beat him in ten forget it. I think a lot of fights might be more exciting and some fighters might take a few more risks with ten rounds rather than twelve. Just my 2 cents.
My late Grandfather thought they should bring back 15 round contests for World Championships Fights, but only with 2 minute rounds. Regular contests would then be for 10, 2 minute rounds. And world title eliminator fights, or minor title fights, would be 12, 2 minute rounds.
On average, I tend to agree with You. 12 rounds is often an overkill. Yet, when You get a great one - even 12 rounds does not feel like it's enough. I had that feeling in fights like Golovkin vs Canelo II, Estrada vs Roman II in particular, in recent years. I think it would be good idea if the comissions stopped allowing fights that are not fought for a World Championship (With preferably one world title/dvision) to be fought for more than 10 rounds. I think it would add to a prestige to World Titles, if only fights on that level were fought on "maximum" distance.
Fighters generally know how to protect themselves these days. The key to brain health for boxers is to have fewer sparring sessions. Do not spar like Ali or Toney. Also save up well and retire at the right time. Even if fights were reduced to 10 rounds, you would get boxers who would blow away all their money on hookers and cocaine and end up having to fight too long to make up for it. I personally am not a big fan of 10 rounds as a concept. It takes fighters 2-3 rounds to warm up and really get into the fight. That only leaves 7 rounds of a high quality fight. Not enough IMO. I don't think fighter help would improve or risk would be reduced. You would still get your Chisoras and Whyte's fighting well past their prime to secure more and more paydays.