Yeah, the point is to be able to search beyond file names, like in their descriptions or content.
But the superlong time it takes to index and the huge file it creates are hardly worth it. Unless, I suppose, that you have millions of really old files that you can't remember. what was that thing I had that was about something else but mentioned the phrase "the bee's knees"? who cares.
I had a 100 Meg index that I hadn't updated in about a year. I tried to do it, and it told me it would take 50 hours.