Vlad Closing just one instance on quit surely is a feature that some people will enjoy, a setting to change that would be useful in my opinion though.
Keeping profiles on the dock might give more control depending on how you work, but this implementation removes the sleekness and organizational benefits of having different profiles instead of having whole separate browsers for different purposes... Having this many profiles is probably unusual, yes. Thats why I suggested it would be great to have an option at some point, not that my preferred behaviour is the best for all users and should be the default.
Having the option to do it this way might also make it easier for users to migrate from Chromium-based profiles, as they behave the way I described above?