Lets start with "ugly", Aurora. I can remember getting a P-40 kit from them at at the age of 8 was thinking, "this isn't right".
I can remember getting various ships. Ships are hard and even back then the box was filled with dozens of pieces, there was definitely more engineering & research needed Conversely, it's a fair bet that some of the people who put together the air recognition rubber models used in WWII found employment in the '50s as plastic model makers. That means the airplane people had an advantage right off the bat. They were working in balsa or rubber before going to plastic.
I introduced my grand-nephew to modeling. I painted & put decals on a Lindberg 1/48 model F-80 for him. I wished the plastic was not a sickly white. But the kit is fair and not that bad. I consider Monogram's "about" 1/48th scale P-40B, P-39, and BF-109 to be very good for the time. Indeed, the P-39/P-400 holds up fairly well for a kit from the 60s.
If a ship is really screwed up you pretty much can't fix it. Conversely, Testors/Hawk has an elderly 1/48 F2H Banshee that could be fixed/updated by pirating parts from a Monogram F9F kit and scratch building.
Revell wins the prize for a excellent job in the 1st Generation ship models with the following ships: Constitution, Kearsarge, Alabama, and Cutty Sark. Indeed, those beautiful ships could be argued the beginning of the 2nd Generation. Real research and craftsmanship can be seen.
I'd say more than a few posters on this site would buy the 19th century USS Kearsarge or CSS Alabama in 1/96 scale if Round2 got the molds from Revell of Europe.
Anyway, my point is some of the 1st generation airplanes are not that bad. Ships? I suspect some of the ships were conversions of WWII drawings from a magazine, like Popular Mechanics.
I also mildly remember that some of the model manufactures caused a brew-ha-ha for making a fairly accurate model of the USS Skipjack. It was felt the Soviets would copy the hull design from a plastic model. Since many 1950s and 1960s US Navy ships were upgraded ships from WWII then the general feeling may have been "only boys will have this and let's not give the Soviets any help".