The path in quotes - a rule of a good tone. If the path contain spaces, then the command line without this quotes can be interpret incorrectly.
Do you guarantee that your case always will work normally?
Bright example - Opera 9.63. Developers have forgotten to put inverted commas in transfer of a command line. Try to use oGet on Opera 9.63 and you will see this:
In this case (Defraggler) all work fine, but...
I thought it it is known to everyone who is not only the user.
If don't trust me, then look at registry entries from known software products like: Adobe Reader 9, Foobar2000, Foxit Reader, Nero, WinDJView, WinImage, Wordpad))), Daemon Tools, Media Player Classic, Photoshop, and so on.
Well... I have warned you.