There’s the book called Otaku: Japan’s Database Animals where the author suggests that Evangelion more or less popularised moe. It’s not that moe was nonexistent before, let alone in the context of having profound sentiments towards arousing or interesting traits that can be taken out of the series’s context. Like online memes.
Such memes may’ve existed before with fans making superdeformed versions of Gundam robots and characters as well as anthropomorphising the former. So on and so forth in addition to fan smut. (Keep in mind Star Trek slash fanfiction existed before and more or less popularised such a word to indicate fanmade homoerotic pairings.)
As well as alternative universes where the same author assumes that one Evangelion episode seemed to be inspired by a fanfiction. The odd fact that Evangelion might be one of the first anime to feature or popularise out of character merchandising makes me think he has a good point about it popularising moe.
I’d say out of character merchandising did exist before but not very often as to be thematically consistent and even today it’s still being done. It doesn’t matter whether if Supergirl wears a slightly different version of one of her former outfits (I can go on arguing that her one-time leotard and her New 52 outfits are reiterations of her 1970s hot pants ensemble), it’s still consistent with what’s expected of her.
The same can be true of any franchise, including both Evangelion and Gundam. Given I have a feeling that out of character merchandising more or less increased during the 1990s, which’s more or less the same time Gundam started doing alternate universe productions (though sometimes returning to the original Universal Century continuity), which Evangelion eventually followed suit.
I could go on saying that some Gundam productions, as far as I recall, are thematically consistent in having an anti-war theme, a red-clad or masked Char Aznable character and young characters thrust into such situations. Evangelion turns this around where familiar characters get thrust into entirely different situations and stories.
That and spawning a lot of characters that are reminiscent of either Rei Ayanami (shy, odd hair colour) or Asuka (fiery, blond or orange twintails though Ideon’s Kasha Imhof got there first). That’s not to say Gundam’s not moe as it spawns memes and the like (so do other anime franchises). What makes Evangelion more moe than Gundam’s that familiar characters get placed in very different situations.
They may even be dressed out of character or seemingly so, which I think would’ve further popularised the already existing trend of putting characters in OOC situations in merchandising. The fact that it’s not uncommon for Evangelion spinoffs to put familiar characters in very different situations and stories sort of proves the database consumption theory right.
In the sense of going after characters regardless if they’re put in entirely different stories instead of underlying themes and the like. Again not always the case but I’m getting the impression that Evangelion’s moe for putting familiar characters in very thematically different stories.