From my perspective though (as both a ST fan and a long time reader of the Titan novels) it's unnecessary as the fact that the crew is diverse shouldn't be a big deal from a Federation perspective.
In theory, no, it shouldn't be. However, the novels are constrained to be consistent with onscreen canon, not with our ideals or wishes of what ST should be. And regrettably, limitations of budget and sometimes imagination have resulted in a canonical depiction of a Starfleet that's either highly human-dominated or highly segregated between humanoids and nonhumanoids. So if we want to do a series that takes more advantage of the freedom of prose to depict diverse nonhumanoids interacting on one ship, it's a matter of consistency with canon to acknowledge that this is a departure from the norm.
Hopefully future novels can foster a greater 'sense' of Starfleet crew diversity without it being pointed to as an example of diversity, but rather the status quo. (if that makes any sense whatsoever).
That is the hope. The greater integration of the Luna
class crews was intended as a pilot program. If it worked out there, it would promote more widespread adoption of the practice.