I remember resisting myself as a kid the change from DOS to Windows versions of apps. Practically I was more productive with my memorised key combos and found it extremely annoying to switch. I also had an Amiga background that "workbench" and mouse point-and-click interfaces in general were meant for design and authoring applications but not for documents. Coming to think of it, I still feel this way - which perhaps is why I'm so naturally inclined to use stuff like vi(m)/emacs and tiled window managers.
The only other comparable stack of the era, maybe slightly later, would be MS Access. When you’d get a call from a prospective client who’d explain they had a member of staff leave and now nobody knows how the Access database works.
“Accidentally load bearing” is an apt term
When I was manager of a Macintosh network in the early 2000's, we were forced by corporate to use Lotus Notes. Not a single person enjoyed using it, and nobody on my team enjoyed servicing it.
It would be hard to recreate the experience since it relied on a network to get the full experience. Instead of Notes maybe give Multiplan a go. Horrible Microsoft also-ran of a product but interesting to reminisce about.
It will beats outlook as a mail client in a lot of ways, such as having actual usable full text search.