You misunderstand what -f does, however you are right that it is used all over the place by default and it does add more risk than not using -f. However you're wrong that the lack of -f is risk free. Unfortunately even without including the -f flag it is still possible to delete "important" files given that "important" can mean a spectrum of things, both in terms of file system metadata and in terms of personal worth.
In fact `rm`doesn't even try to understand what an important file is (and why should it?). All the -f flag does is ignore prompts and non-existent files:
$ man rm
...
-f, --force
ignore nonexistent files and arguments, never prompt
...
I think it also overrides skipping the removal of files that don't have a write bit set (despite that not being explicit in the man page) but even if that's also true, you're going to have a crap load of important files that are still writable. Thus it's still quite possible to trash your host using `sudo rm -r /`
You might then say "so you shouldn't use sudo either" and that's true. But going back to my earlier point about "what is an important file?", you're still going to have lots of "important" files on your system that aren't root owned. Maybe development files. Maybe personal files. Thus it is trivially easy to remove wanted files with a careless `rm -r ~/$UNSET` (a bug in Steam's Linux installer once did this in fact).
So the benefit of -v isn't mitigated by the non-inclusion of -f. Not even slightly.