The problem being that, unlike J. Jonah's Hitler moustache and R. Lee Ermey brush-cut, there's absolutely no consistency in how the Osborn cornrows are drawn - seriously, look at the hair as drawn by JRjr, Deodato, Jiminez or any number of other artists, and other than the fact that it looks like lines instead of actual human hair, there isn't even any internally consistent pattern in HOW the cornrows go, which is yet another reason to shitcan it (see also: Hank McCoy's lion-esque appearance, which absolutely no one other than Frank Quitely knows how to draw, and since Quitely is long gone from the books ...). Yes, it'd be an adjustment at first, but once again, no more so than any number of other sweeping changes that Marvel seems perfectly comfortable with disposing of, and (unlike the marriage retcon) in the long run, it'd be a change for the benefit of the characters.
It's like this - if you have a character that you're insisting that your audience take deadly seriously, but one of their minor traits is so stupid that even other characters comment on how stupid it is, in the story itself (see also: every character from Deadpool forward noting that the Osborn hair exists absolutely nowhere in nature), then it's a good sign that it needs to be dispensed with. If a character is so inextricably associated with such an absurd trait that you can't risk changing the trait without people feeling like you've "ruined the character" (I know you're not saying this, but still), then the character itself has become nothing more than a nostalgia object (see also: Archie and his waffle-hair, or Jughead and his nowhere-outside-the-1950s headgear).