I use fingerpicks almost exclusively (plastic thumbpick, metal fingerpicks), but wouldn't necessarily advise anyone else to do the same. I'll pick barefingered occasionally at home, especially when I need to be fairly quiet (late at night, etc.), but wouldn't perform without wearing my picks.

I've been using them for so long that I have more dynamic range and more confidence with them than without. Also, I eventually learned not to have them pop off my fingertips and disappear into my soundhold (well, hardly ever); when starting out, that happened *all the time* and drove me nuts.

I tried (briefly) the thumbpick-and-bare-fingers technique, but couldn't get the sound to balance -- bass notes played with the thumbpick would come out too much louder than the bare-finger-picked treble notes. I'm sure this can be overcome, since plenty of players use this style, and the similar flatpick-plus-bare-fingers approach, but it's not for me.

Also: what works for electric (and even acoustic-electric) intruments won't necessarily work in a completely acoustic context. Amplification allows the player to use the inherently quieter barefingered approach without sacrificing volume. Just because Mark Knopfler, Snooks Eaglin, et. al., can produce highly dynamic music playing their electric axes barefingered doesn't mean that you (or I, or anyone) can get similarly good results barefingering an acoustic guitar.

For anyone learning the guitar, I'd say try every technique -- flatpick, fingerpicks, barefingered fingerpicking, pick-plus-two-bare-fingers, whatever else, etc. -- and then decide whether to choose one approach or to go for versatility.