GoZ for splitting teeth as a group separate from Gums needed for custom shapes and painting
Its insane to try to customize teeth currently. If teeth were sent to Zbrush separated as a group from the gums we can always mask out or hide individual teeth to position them quickly otherwise it's a tedious effort to reshape, paint and make the design custom overall.
I was spending a lot of time on finding a solution to the polygroup issue in Zbrush breaking the UVs and essentially your character and in the end I realized that's what the Goz splitting is likely mostly about but isn't talked about in that way as THE solution otherwise why are people making the mistake of using polygroups? because they need to do more complex tasks since the part they are working on lacks the ability to be worked efficiently to save time.
Lastly I think the GoZ window should have tips/warnings such as "DON'T USE POLYGROUPS OR IT WILL BREAK YOUR CHARACTER!) so you're reminded not to destroy weeks of work, make sense? I think so.