No, they've done storylines about how very, very smart he is before -- it's just that they're rarely, er ... very smart? Like the one where he number-dropped his IQ and it was higher than actually possible, when the writer could have spent two minutes on Wikipedia to come up with something plausible. Or the big 600, where we're basically supposed to take the fact that Spidey wrestled Ock's "control New York with MY MIND" machine with his brain as proof that he is smarter. Admittedly that was fairly cool, but ... a) why was that proof of intelligence? b) we weren't really shown the struggle, we were told about it.
Compare this to JMS' run. JMS isn't a scientist and you can tell, but you can also tell how important he thinks it is to show that Peter's a scientist, and to show what being a scientist means, both in fact and in philosophy. Peter researches solutions to answers he doesn't know and looks up things he's never seen (the "what's a spider-wasp?" moment was classic). He enjoys tinkering, and he becomes a teacher so he can try to pass on a love of the sciences to the next generation. (His speeches about the JOY OF SCIENCE are almost OOCly eloquent for Peter, who is snappy but not usually so poetic, but then he accidentally orders The Joy of Cooking as the class textbook, so I can let it slide.) In fact he teaches even when he's not teaching -- there's a great one-shot issue in which he defeats a knock-off Shocker villain by dumping him into a swimming pool and letting the ensuing literal shock waves pound him into submission while he stands by the side and explains the physical processes involved to the pool attendant.