If you really want to do something about malware, disable javascript by default.
What if you want to do something about malware, but don't want the hassle of re-enabling javascript when you actually want it to work (because, contrary to popular belief, it can actually be employed usefully)? What if you're too lazy to install another piece of software, or just don't want to install another piece of software? What if, god forbid, someone has different an idea on what to do about malware to you?
"Automatic handling of pdf and ogg files" - I have a pdf reader already. I dont need another one
Well, good news! Because as you carefully omitted to quote, "...if no other software is available to do so." So it'll be just like you don't have another PDF reader.
TL:DR; this isn't how I use computers, therefore this isn't how anyone should use computers