Given how much of the app is tied into the UI, a full rewrite would seem to be exactly when you'd want to make any major UI changes. I've been in that spot a fe

Given how much of the app is tied into the UI, a full rewrite would seem to be exactly when you'd want to make any major UI changes. I've been in that spot a few times myself and the last thing you want to do is re-create the old UX on a new codebase before implementing the UX you'd "like to have". In a perfect world you might even want to do the UX change first then rewrite the back end, but in reality if you did that you'd probably worry about losing support for the rewrite of the underlying plumbing once the new look has been deployed, since management often thinks of front-end refreshes as "delivery" of a new system.