yeah, this shit perplexes me too. my takeaway is that gainax absolutely needed to include heapfuls of fanservice, either because they liked that stuff themselves, or for economical reasons (they did release adult games featuring their own intellectual property just to stay afloat). if they'd played it straight and depicted the characters the way kids that age normally look, then there would be zero ambiguity as to whether or not it's fucked up to use the male gaze on them so much.

but on the flip side, it's not as if they were adapting a manga or light novel. they were absolutely in control of how old those characters are. so unless it was completely impossible for japanese audiences in the 90s to accept shinji as being any older than 14 due to cultural beliefs about how quickly boys should develop into mature adults, I really can't think of any reason for the Eva pilots being canonically so young. it's also understood that much of the sexualization in NGE is directly from the point of view of a hormone-laden teenage boy, but that phenomenon persists well into adulthood especially if the subject happens to be a repressed nerd.

with all that said it's probably better to bump the wrinkle and subcutaneous fat sliders way up just to be safe.