The NY Times had a piece on that question I thought was interesting.
https://archive.ph/y5GYy
My kids are in public elementary school and we've never gotten any pushback on missing some time, although we've also never scheduled to miss more than a week.
There are some advantages, it's often way cheaper and less crowded where you're going, but obviously you're missing class. Adding a week to spring break also gives the opportunity to take a 2 week trip which opens up destinations considerably. For instance I'd really like to do Egypt/Israel (maybe not right now, precisely) but summer isn't reasonable, Christmas is $$$$, and 1 week is too short for a trip that far, so an extra week at spring break seems like the option.
I sort of also feel like that becomes less of an option as kids get older and have more serious classes, more extra-curricular activities/sports, etc.