Hello, Currently we ship Tor-browser with default settings which is fine for normal usage, however since if somebody bothered to set-up whonix it means they want the highest level of security and thus making tor browser default to Safest mode by default should help a lot
That is the decision by The Tor Project, the developers of Tor Browser.
It would be nice to change this at the Whonix level but difficult to implement. Same answer as here applies:
UBlock Origin and the "Safest" tor browser setting - #2 by Patrick
That’s fair, thanks for clarifying. and yes I read that post but I thought you only opposed the additions and not security level change