^^^ well, Given that for the most part, the workhorses of the fleet are of a design 3/4 of a century old (granted, with upgrades/modifications) and given the severe pounding Starfleet has taken in the last decade or so, why wouldn't the engineers design new
ship types that could stand up to the kinds of threats that the Federation has been facing recently? Yes, there have been a lot of new designs recently, but building a variety of types of ships allows Starfleet admirals not to put all their dylithium crystals in one warp core, tactically speaking.
As for the image as a starting point, works for me. It feels a little too much like the Dauntless
for me, so I'd give it a more Luna-class and/or Sovereign-class style.
Given its crew compliment and classification as a "multimission explorer" it feels to me as though the Vesta
class could be working its way to becoming one of the main workhorses of Starfleet (experimental results affecting the speed of this development, of course). Which is cool with me. I think we've seen the Excelsior-class in this capacity for too long.