Nowadays it does not seem all that important, after all, most people are getting away from even using pens, but in my school in the eighties, ink that could be erased seemed like magic. It was especially useful when you had a stickler for teacher when it came to penmanship. Most of my teachers fell into that category and would force us to write our essays in pen. What made this difficult is that you were not allowed to cross anything out.
This meant that if you wrote four paragraphs and made one mistake into your fifth, you had to start completely over. You were supposed to get better at writing by having to practice again and again. Instead you usually just wrote the same essay six times It was a nightmare for a typo prone person like myself.
When the Scripto showed up, it was like an item out of mythology. Now just like with a pencil you could correct errors.
If I remember right, these things were not cheap. So I was maybe budgeted one or two a school year. Losing one was a minor tragedy, which I did often, and often my mother would just tell me I had to suck it up and make due with my old school pen.