It seems like deployment of VSTO code is very cumbersome.
My use case is I need to enforce a certain content structure in word. Am I better of doing it all in VBA?
It really depends on what makes most sense for your project. If it's only going to be for certain files and a couple users, I would recommend VBA.
If it's more complex and needs to work on all files for all users, I think a VSTO plugin would be the way to go. It really depends on your situation and complexity you're trying to enforce.