Yes, you're right, DVD Player can read VOB files, as long as they are still toghether in a VIDEO_TS folder (that is, a valid DVD). VLC can also open VOB files, even separately, but (1) I edit my movies, like cropping them or exporting the audio (which VLC can't do), (2) I often want to open a folder full of VOB files, e.g. to compare them or to rename them in my workflow (VLC can only display one at once) and (3) VLC is a garbage software, really (it's playlist-based, so it loads the movie files from previous sessions (I often open a single file per row, play it, and VLC loads another when it has finished; clearing the playlist for every single file I open is unreasonable)), it also never shows correctly the duration of the playing movie, clicking on the “time” bar is never accurate, no keyboard shortcut to navigate (e.g. frame by frame) and many keyboard shortcuts are just missing or weird. (4) I use QT7 for everything else (movies related).
Thanks for your answer; unfortunately, only QT (pro) suits my needs for editing purposes (and I'm not talking about commercial movies, just files I've recorded myself which ends up in VOB (a DVD burner)).