Yeah a few individuals are having a real problem with the new reality... personally I am loving the new ship sizes, I think it is more realistic and an understandable response to the Narada incursion and destruction of Vulcan.
I wouldn't call it "realistic", but justifiable. It's my understanding that real naval vessels are as small as possible for the requirements.
But it's not justifiable from a function point of view. Making something "bigger" because of a threat is nonsense. An adversary won't be intimidated by the size of a weapon, but rather by its effect (see: nuclear bomb delivered by one plane, vs firebombing via squadron -- which caused the Japanese emperor to surrender?).
The ships in the Abramsverse are big for ONLY ONE reason: they wanted the shuttle bay to look like it could land 1000 troops at once. For some reason, the transporter is no longer the favored method of getting from land to ship.
So, one is free to "justify" why the ships are big all they want. But in the end, it came down to one person saying "Hey, wouldn't it be fucking cool if there were, like, 20 -- no, 30
fucking shuttles parked at once?!!!" (homage to the Lindelof interview posted elsewhere).
I'm reminded of the scene in Weird Science where the jocks force Gary and Wyatt to make them a woman, and insist on the breasts being incomprehensibly large -- "BIGGER! BIGGER! BIGGER!". I wish I could find it on You Tube, but alas.