I've never liked that analogy, that Gunbuster is about "not wasting your life". Whether Anno said so at a later date or not, it's not what it presents at all. Yes Noriko stays young while others grow old, but if anything, it casts her as someone who, while fully aware of what is going on and utterly terrified of it, fully accepts the weight of what it is she does and ultimately *embraces* what is is and what she must do and never looked back.
The Gainax of the era that produced Gunbuster also produced Otaku no Video, a deliberately tongue-in-cheek homage to the otaku culture. They weren't *opposed* to the otaku culture of the time, they *espoused* it. One of their head producers even took on the title of real-life "Otaking".
Eva, on the other hand, is Anno telling the otaku to go out and get a life and Diebuster continues that more pessimistic outlook (the Topless presented as spoiled children, Buster Machines given away practically like toys in wrappers, etc.), but that's not what *Gunbuster* presented.