There have been plenty of arguments made in favor of spikes as vibration isolators. Heck, I use spikes under my Studio 60's. I think that having a speaker on some sort of supports so that the bottom of the enclosure isn't flat on a floor surface is a wise decision.

But... There's one aspect of the arguments for spiking as vibration isolation that I've had a hard time with, and it's at the root of what bestbang4thebuck has so well addressed. If we look at the way we handle vibration isolation with rotating machinery (fans, pumps, compressors) and the one thing that we always see is flexibility: either springs or rubber isolation pads. A small point of contact will still transmit energy without that flexibility. A more optimal mix would probably be something like the spikes that bestbang4thebuck describes: a reasonably small point of contact with the floor for "controlled coupling" (I like that term) plus an absorber component between the point of contact and the body of the speaker to handle the vibration isolation.