Is Erase function necessary?

I just bought a brandnew 3TB WD Mybook External hard drive for Windows, what if a thief steals it (password protected)? of course he doesn’t know the password, but he can erase all my data without knowing my password, and my hard drive will become his, my data will be lost. I think Erase function is not necessary, especially if someone may deliberately try to irritate you by erasing your all data. 

The erase option is the only way to regain access to the drive if the password is lost.

The reason for the password protection is to protect your data in the event of theft.

If the drive is erased , even when the drive will still be used the data will not be accessible.