I suspect it must have been part of "let's try to secure / lockdown office", "users writing codes is bad, they should only push buttons", and at the same time they tried to make it as hard as possible to use VBA (all sorts of warnings and things disabled by default, etc)

I am also aware of a commercial product that offers a .net IDE to be embeded into your software, though I never tried it: https://www.alternetsoft.com/products/scripter