If you've ever seen those pointy legs on a kick drum, people might think it's to stick into the floor to keep the drum from sliding. Well, that may be one of the side benefits. But the purpose of the spike is to "decouple" the drum from the floor - allowing the energy to drain - rather than remain in the drum.
You can see this also with the use of inverted cones under audiophile speakers, turntables, audio equipment, and audio storage racks. The purpose is to "decouple" and drain the energy moving through the various components.
Contrary to some popular believe, components and bodies can not be "isolated." You put a big piece of foam under a speaker and isolate it - because you can't isolate the speaker from itself. So, even with foam under it - the energy doesn't drain. In fact foam can make it even worse, because you're adding an acoustically absorbant material to the structure of the speaker, making the body of the speaker even more dead.