Why does Ubuntu, and any other unix system for that matter what you to use "remove recursively" for folders or copy recursively. I can only imagine it's a security thing but the name recursive doesn't imply such a thing.
It is mostly for historical reasons. The following is a slightly modified extract from an excellent article named A Brief History of the 'rm' and 'rmdir' commands.
A new version of
rm, dated January 20, 1973, included these options:
rm -f: don't ask before removing read-only files
rm -r: recursively remove subdirectories
The way the
rm -roption was implemented at that time, when
rmencountered a directory among the files it was removing, it would
chdir) to that directory and start another instance of
rm -r *to remove its contents.
A version which did the recursion within a single
rmprocess appeared in the Seventh Edition of Unix in 1979.
More about the history of
rm can be found by following the link above.