IIRC boxing gloves are just as much to protect your fists as stop you battering the other guy.
Even with gloves it’s pretty common for cuts/gashes/bleeding to occur when someone is hit in the head. If they can’t stop the bleeding, or the cut reopens matches can be forced to a doctor stop AKA sometimes a technical knockout.
There’s a reason pro boxers aren’t supposed to get into street fights.
If a fighter in a pro ring takes enough body blows he’ll start having trouble getting enough oxygen and could start showing signs of cyanosis. Again, an uppercut to the chin/jaw/solar plexus can be devastating for any number of reasons, notably concussion.
For the last point, it’s actually a damn technical sport. Power boxers, endurance, technical specialists etc…
Some matches can be absolutely amazing. The only problem I can see is that depending on the weight class, some would need to bulk up or lose horrendous amounts of weight in time for the match (remember rocky sweating like hell? it’s that.)
Thankfully that wouldn’t really apply in a survival situation.
That said, if you could use martial arts with brass/spiked knuckles everything would be glorious. Can’t wait until it’s implemented.