The akira refit is T3, their overarching plan is to have a C-Store ship available of each catagory at each tier. So far they've got the Venture, Excelsior, Rhode Island, and Nebula. Plus the three alternate T1s. And will shortly have the Sao Paulo, Thunderchild, Exeter, and a Saber variant that they didn't have a model for as of STOked visit to the studio.
The Thunderchild only feels like a rip off because we got retrofits for the big iconic ships (Galaxy, Intrepid, and Defiant) at T5, and because of that, when their T4 equivalents got +1 ships they also threw the skins on the T5 refits for zero effort. (though I really wish they'd open up the Celestial and Envoy parts for the Refit Exploration cruiser)
As to why we can't just upgrade ships, I'd imagine that would be word from on high at CBS, cause they don't want a Miranda running around with more guns than a Galaxy spreading destruction in it's wake.
If it's T3, then serious disappointment. Great ship like that deserves better.
Is there rationale as to why we can't simply expend dilithium/EC or something to upgrade the ship we like to the next tier specs (hp, move/turn rates, consoles etc).
I agree, their should be some sort of system for upgrading ships and keeping them as a viable option for longer. What's the harm? A captain should be able to fly the ship he or she wants throughout his or her career. Granted it should not be easy or cheap to accomplish this and just getting a new ship should be the best option, but if players have the time and the resources, they should be aloud to upgrade lower level ships.
Now, before anyone harps about the ships being either to old or sub-par for upgrades or more weapons crew, I'll remind you that we already have some ships in-game that are ancient and have been upgraded to maximum potential. *Cough* *Excelsior* *Cough*
Think of it this way, in the two part episode "Equinox", the Nova class science vessel had been plainly upgraded past what it was intended for, there is no reason why any other ships couldn't be as well.