There are 2 existing suggestions related to increasing the 1000-character limit for suggestions (https://dogfooding.featureupvote.com/suggestions/9304) and the 500-character limit for comments (https://dogfooding.featureupvote.com/suggestions/29940).
(Just including those 2 links took up nearly a third of my character limit before I edited out the suggestion title from the URL (here's an idea related to shortened idea links: https://dogfooding.featureupvote.com/suggestions/79428)... And now I'm at half the limit.)
Anyway, my idea here is simple: let people go over the limit when typing, instead of literally preventing them from typing even a single comma more - and only require them to edit it down to the character limit (whatever it ends up being) just before posting the suggestion.
Some people like to get their thoughts down first, and worry about editing afterwards. It's annoying to have to start trimming the post while you're in the middle of putting your thoughts in writing.