There really aren’t that many power users when compared to the total installed user base so the backup utility may not be a fiscally sound area to invest resources.
Based on data published over the years, the vast majority of Smartthings users have 15 devices or less. With the installed user base having so few devices, and most likely simple automations with stock device handlers, rebuilding a setup because of a new hub becomes less of an issue.
I do agree the prospect of having to rebuild is anxiety inducing though. I am still running on a V1 hub with 150 devices in my list. The lack of backup/restore is one of the main reasons I’m still on V1. The other reason is my hub is stable because I no longer receive firmware updates.
If local processing does take center stage though, as indicated by SDC2019, I will most likely be sending my bride on a long weekend away and take the plunge and start over.