I've never understood why a lot of people seem to like this fat little ship, but I appreciate it. Looks very nice, XFoz!
It's all personally subjective, of course. Here's my theory, FWIW.
It all goes back to what Spock said in "Balance of Terror". He recited history of the Earth-Romulan Conflict of approximately 100 years pre-TOS during his address to the crew. Spock spoke of a war fought with "primitive atomic weapons" and "primitive space vessels which allowed no quarter, no captives". People's imagination ran away with that. Look what Goldstein & Goldstein came up with in the 1980 "Star Trek Spaceflight Chronology", which, in some respects, was a precursor to Masao
People saw Khan's S.S. Botany Bay in "Space Seed", and they saw Kirk's Enterprise. Small wonder that fans over the years haven't come up with even more funny-looking specimens to fill in the evolutionary blanks.
There's a great deal of apparent logical thought behind ships like the ones in the Museum. It's too bad we didn't see more of that in ENTERPRISE.
All that said, I can't help but to see hints of 2001: A SPACE ODYSSEY and even SPACE: 1999 in the Museum ships. They definitely look closer to TOS art than with the Goldsteins came up with in 1980. Still, ENT, for all its flaws, still casts a shadow.
For me, the Museum ships have nacelles that look a little too divergent from TOS and ENT. (Of course, to be fair, I understand the Museum to have been originally conceived prior to ENT.) The Phoenix from FIRST CONTACT should be factored in as well. (Ironically, the ENT ep "First Flight" scored a huge artistic success with the NX-Alpha prototypes; too bad we didn't see more of this.)