The use case is:
When I share dashboards, I already avoid the Designer role. That's fine, having the extra option on the drop-down doesn't matter for my use.
But others also make and share dashboards. The owner and the designer-role users don't know exactly how Republish and the Designer role works. Sometimes, a designer will change a widget without realising their change could be overwritten, and the owner will republish without realising that they're overwriting others' work.
The other problem is "I fixed the formula on the dashboard you shared" followed by "I don't see the change" because the user actually fixed it on their Designer-role version of it. Or "Why doesn't your version of the dashboard look like mine?".
When sharing comes up in conversation with others, I advise them "Never use the Designer role because it's bad", because otherwise it's a lot of confusing explanation and there's enough other confusing stuff to think about.
Part of the appeal of Sisense is that it's intuitive. Removing the designer role will make it more intuitive.