Just saw this after reading about new Outlook on the consumer side, and much of it is more relevant here:
Really hoping to hear more soon about what is being done to bring true parity with COM add-ins to modern add-ins. I've only seen mention of this, nothing concrete. In comparison to COM add-ins today, modern add-ins are:
- Very, very click-heavy (few UI integration points; any actual functionality seems always to be kicked to a side pane that has to load)
- Exceptionally limited (can take action only on one item at a time)
- Molasses-slow (seemingly a complete reload per item, no state info)
- Not scalable (a side panel might be workable if you have only one substantive add-in--if you have a wide enough display--but 2 or more? Even if possible, the UX is awful)
On the plus side, greater stability and servicing simplicity are absolutely big wins... but nowhere near big enough wins to offset the issues above. I fear that, in the push to retire classic Outlook for Desktop, "parity" (and thus retirement) will be declared long before anything near parity (if ever achieved), as happened with Teams vs. Skype for Business and many other examples.
Until there is clarity on the modern add-ins issues and many others, I watch the march of new Outlook with a sense of foreboding, not anticipation.