I mean, I do like so-called "Nu-Trek", but at the end of the day this is kind of a tail-wagging-the-dog response. You can explain just about anything in lore after the fact, but when the rubber hits the road the real explanation is that someone in a Hollywood design team said "We want it to be BIGGER," and then left it to the people who cared enough to find a reason why it would be justified.
Far easier to just suspend your disbelief a bit further, I think. Yeah, Discovery is weirdly big. It also flies through space by a man infused with a giant tardigrade's DNA sending the whole ship from place to place through willpower and a mushroom trip. If you can accept the second one, it kind of feels like the fact that the ship is a larj boye isn't that much of a stretch.
I guess I just fundamentally don't agree with the need for a "backsplanation". I am of the camp that I'm totally OK with the Klingons looking different in TMP than in TOS because it wasn't a 1960s TV show anymore and they wanted the aliens to look more alien, and that's all the explanation that I need. The Enterprise is different between SNW and its appearance in Discovery because it's a different show and they wanted to tweak its appearance some to make it more of a "hero" set. Spock and Sarek never mentioned his having an adoptive daughter/sister in spite of being in two series and a half dozen movies because Michael didn't exist until Discovery and the writers thought it would make for an interesting tie-in.
I have enjoyed the series since TNG in the 80s, and I'd love for it to come true some time in the future. But it's a TV show, it's not a history book. It's fine if there are inconsistencies, none of it is real anyway.