Comment 12 for bug 78505

"In Ubuntu, we intentionally set things up using binfmt-support so that
users don't have to know to explicitly invoke things using wine; they
can just execute the .exe file directly."
AFAIR, having wine as the default app for .exe (just like gedit is for .txt) is enough - exe files can be run just by double-clicking. No need for +x for the whole fat partition, no change for users' expectations.
Besides, when you have a Windows app installed on a Linux partition then you won't benefit from +x on fat/ntfs - you will still have to set +x manually or open it with wine (double clicking or by CLI).