I've been exploring this concept a bit at my startup for our B2B offerings. Where I've landed is a robust set of feature toggles that Sales and Account Management configure. Within the confines of your Microsoft Word toolbars analogy; since the software we offer is similar to SaaS and delivered via a web browser this effectively means we can "hide" the toolbars that the client isn't interested in.

This is all pretty early days, but my hope is that we can iterate the core "have feature toggles" concept to the point where we have the ability to turn functionality and function accessibility on across many verticals. I hope that one day internally we can configure things a per-customer and per-user-persona basis. I also hope that one day we can expose some of those switches to admins and/or everyday users, possibly with paywalls or other strictures.

We'll see where it all lands :D