Expanding on this ask, I feel like SEED’s frequent callbacks to the Universal Century did a lot more to hinder than to help.
Their primary purpose, i.e. keeping previous series fans onboard, backfired when mixed with the idea to simplify the narrative for accessibility. By so clearly using 0079 and Zeta as basis (for the first half of each SEED show at least) for the overarching structure of the story, comparisons are unavoidable, and likely unfavorable, considering aforementioned simplification and the fact that the UC series in question had around 20-some years worth of nostalgia and rose tinted glasses built up. (You can see a similar phenomenon with regards to AGE.)
And on the flipside, if they hadn't adhered to the UC plot as much, they could have more closely tailored the setting and story beats to fit with the human drama and romance focus they were trying. This would likely have helped it gain an even larger new audience, and a lot of older fans likely would have recognized it as, and given it more respect for, trying something new, even if its not necessarily right up the old fans alleys. (esp. considering that G and ∀ had already given the format an extreme shake).
I guess as a tl;dr, i get the sense that overall, AU’s that stray farther from UC’s setting and structure seem to be better regarded by series enthusiasts, while also being very popular and inclusive of new audiences in their own right. So if SEED had just been able to freely explore its own unique niche, I feel like we could have had a really good series, both commercially and critically.
