It's important to remember that we never met 616 MJ in high school. We met her in college. When people think of High School MJ, they usually think of Bendis' USM which rewrote her personality.
The actual MJ in high school was glimpsed once in ASM#259, and here she is:
ASM#259(Ron Frenz) - MJ in High School.jpg
MJ in high school in 616 was a class clown, socially awkward, and a little weird. She didn't become Romita Sr. charisma machine overnight. Zendaya's MJ is very much the version of MJ in that issue. The point of Defalco's story, and Roger Stern's Daydreamers before, and Parallel Lives later is that the Lee-Romita MJ which is unfortunately the template everyone has in mind for "authentic portrayal" of Mary Jane, is not in fact the real MJ. The real Mary Jane is the character from ASM#122 (Epilogue) onwards.
I remember how people pilloried, and still do, that Kirsten Dunst's MJ isn't the real MJ, and the main idea that comes down to is holding her to the standard of Lee-Romita's MJ, when in fact that's not really the character she's been since forever. Like the X-Men with Claremont, Mary Jane has been totally revised by Conway, and later Stern/Defalco and others. The Mary Jane of Bendis' Ulitmate Spider-Man, the cartoons, the video game, the Raimi movies, and so on, is the Mary Jane who loves Peter and loves Spider-Man, is the one who is his confidant and best friend. That's who the character has been. In comics, not even OMD went Pre-#259 in terms of characterization and story. Mary Jane is a hard character to adapt, just like Peter Parker, because she is one who changes and grows.
And you can't really tell that story of growth without making both of them older and wiser. So whatever problems people have with MCU Spider-Man and MJ, a large part of it is because it's teenage, because it's focused on Iron Man, and because it's not a love story.