I wasn't thinking about Galactica 1980 (which is loved by few ) as much as the original 1978-79 show which had a high budget and ratings decline despite it's initial popularity.
Yes, I know, but G80 helps illustrate the point I was making about Larson's excessive spending being a factor in the original show's failure.
I could see Phase II taking a similar trajectory, not to mention potential conflict between Roddenberry and his co-producers (as did occur during the production of TMP) which might lead to a premature cancellation.
That depends. If they'd brought back Bob Justman as a producer, that would've helped enormously; Justman was the opposite of Larson, an expert at producing TV economically and avoiding waste.
There's also the fact that Battlestar Galactica just wasn't very good. It was an attempt at a very ambitious sci-fi epic from a producer whose usual output was schlock like BJ and the Bear and Manimal, and Larson and his staff just weren't up to the challenge. The series had its moments, but overall it was nowhere near the level of Star Trek from a writing or intelligence standpoint. If Phase II had happened, presumably it would've aspired to a smarter level like the original Trek, so there just wouldn't have been any comparison. Between the original Trek and TNG, intelligent science fiction television was practically nonexistent in the US. So a Phase II Trek would've stood out from the schlocky pack as much as TOS and TNG did in their respective eras. (TNG did get some competition in the smart-SF category toward the end of the '80s and into the '90s, but when it first premiered, it was head and shoulders above most of the rest of SFTV in smarts and sophistication, which is why it succeeded with audiences despite its first season being pretty bad compared to what came later.)