M2, and A2 are a different story, they definitely need to be coated.
Bark River uses A2, uncoated. It works just fine and doesn't rust with minimal care.
It's just part of the 'tactical' knife package. Coated, eversized, high-tech materials (ie plastic), over-the-top advertising...
Some guys like 'tactical' knives to play ninja at the mall. Others like them for the quality, unique designs, aesthetics, ergonomics, interesting actions - really the same reasons that us hard-core accumulators buy hunters, slipjoints, bayonets, kukris, and anything else with a blade. Lucky for us, there are plenty of non-'tactical' knives available.
By the way, on my 'tactical' knives, I prefer a bead-blasted finish. Non-reflective for those top-secret undercover missions at the Mall, durable, and it looks nicer than a coating.
Best Wishes,
Bob