If you are a linux user like me, you know the value of being able to password-protect your GRUB entries so even if your whole PC gets stolen, no one should be able to access your valuable, classified data. (or porn?)
When talking of security in computer systems one often needs to analyse the situation one is in and choose the appropriate options. If you have hackers getting physical access to your computer system the GRUB security measures won’t last a second (pretty much nothing would do). Your best bet in such a situation is to keep the hard drive encrypted, or if your hard drive can be password protected, use that option.
However, the majority of us don’t have to worry about hackers with physical access as much as our not-so-computer savvy relatives and friends fiddling around with the system. That is what we have the log in passwords for (they are not secure enough for hackers, trust me!), and that is the situation where you would be wise to make use of GRUB security features.