It's a given that Peter Parker should always be a freelance photographer. The running gag is that he secretly profits off his own superhero exploits and is paid by the very guy who hates Spidey's guts. It would ruin the comic irony if you removed that aspect from Spider-Man, and it's a real shame that the current crop of writers have underplayed the banter between Spidey and J. Jonah Jameson.
Having said that, I believe that JMS did a really good move by making Peter a high school teacher. It highlights that he knows science, it's tied to his working class roots, and plus connects him to his high school beginnings. However, he really missed a golden opportunity to expand Peter's supporting cast by giving him new characters in such a setting, opting instead for brief exchanges with walk-ons and quasi "After School Specials" that attempted to invoke "The Kid Who Collected Spider-Man" (and he complains in the Wizard interview how Spidey lack a supporting cast. At least PAD is attempting to recitify this by having Flash be a PE teacher at the same school.)
And while you make a good argument for Peter being a college professor, Captivated (and let's be honest, when you have a Master's in Biochemistry or BioPhysics or whatever degree Peter has, that's pretty much your career path) I believe that makes him seem older than he already is. While I don't mind him being married or having a kid (someday), Peter needs to stay a relatively young man and a public high school teacher maintains that. Besides, somehow I don't see Peter being in the same category as a gray-haired, bispectacled dirty old man who loves to lecture, or a former 60s radical who still thinks he's young and hip with his students (okay, yeah I know they're stereotypes, but come on. Most of us who went to college know that's not too far off the mark.

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