Here's a 26-year old post on the exact topic of messiness you raise:

https://www.joelonsoftware.com/2000/04/06/things-you-should-...

A decade ago, I was sitting in on a meeting about a rewrite and, before I could say anything, someone in the first year of her career asked why anyone thought a rewrite would be any cleaner once all the edge cases were handled. Afterwards, I asked her where she learned this. She said "I don't know, it just seems kind of obvious." She went on to be a great engineer and is now a great manager.

The bolded quote "It’s harder to read code than to write it." is hilarious given todays context... it has only become more true :)