Vibration is a problem for both F3A and 3D planes, i dont think it's more of a problem for F3A, maybe 3D guys just care less, i don't know..
Less vibrations means more battery life and longer lasting servos.
I don't think that there can be something like too little vibrations on the airframe.
Probably hyde mounts are more popular on F3A planes, because you need to have as much precision as you can and minimizing vibrations achieves just that, by reducing servo pot and gear wear for example.
Should make some sense?