Client api is responsive, fast
If it's done right. So, just like an app.
access to local OS and local hardware
I'm already speaking for switching from Outlook with API to apps, you don't need to sell it to me!
Severely limits access to other services which is very important when moving data.
Read this again.
You're advocating for moving data via Outlook. Mate, I hate to break it to you, but this is peak insanity!
You have conflated User Experience with User Interface. I didnt say UI for that obvious reason
UI is integral to UX. That's why I mentioned it.
Also: "familiar UX" makes little sense. People don't get "familiar" with UX, the UX is either good or bad. That's why I mentioned both.
Having to open and process the same flow of task from one app to another app breaking concentration is bad fucking UX
Here's the thing: it shouldn't be "teh same flow of task from one app to another". Modern apps tend to encompass the entirety of a process.
Something as simple as classing becomes simple when the context of the conversation is very easy to get and more accurate when you dont duplicate an entire chain.
That's what ticketing systems are for.
In general: using email for business processes must die just as much as using Excel for a "database".