I used to pick without an "anchor finger" on the pick guard. It worked ok on electric but it really limited my acoustic playing. On both acoustic and electric guitar there's a drastic difference in the sound you get from picking over the neck pickup/soundhole and by the bridge, and having your pinkie on the pick guard gives you the ability to utilize just that. Think of all the cool sounds guys like Michael Landau and Scott Henderson get from picking all the way back by the bridge, and how Hendrix and Stevie would get great fat tones from picking over their neck pickups....
I forced myself to start using the right hand pinkie, and it's really freed up my playing. I can still use all the other techniques like resting my hand on the bridge. But I have the choice now!
If you wanna see someone who in my opinion has the ideal right hand technique, check out Tommy Emmanuel. He uses the right hand pinkie but is still able to play beautiful fast runs. Check out this video for a perfect example of flawless right hand technique....
http://www.youtube.com/watch?v=gJjRRgTf4Vg
Hope this helps!
Anders