I have also considered that idea, but did not follow through on it. The reason I didn't, is that I have since come to the conclusion that direct coupling to the floor is a benefit and not a detriment. Just as speakers sound better on spikes that directly couple them to the floor, I believe that turntables need this same type of coupling. I realize that this flies in the face of the generally accepted wisdom of decoupling and isolating. Sometimes, generally accepted wisdom is not correct. To elaborate, I think that to get maximum detail and dynamics out of your turntable, it needs to be floor coupled. The coupling itself is to provide needed rigidity for the transducer to operate correctly. Literally tons of PSI are present at the stylus/record interface due to small contact area. Although this pressure is spread out over the full area of the platter and through the spindle and into the base, it is still there. The arm, though coupled to the base at the pivot, has a static balance and effective mass load. It has moment of inertia which tends to keep it in its current state. If the platter/base assembly is allowed to move in any direction whatsoever, the stylus pressure in the groove will be influenced in a negative way. You may say that the arm will move with the movement of the base, but this is not so. Only the pivot end will move with the base and the headshell end will "float" relative to the record. This changes stylus contact and tracking force much like a record warp would, except usually much less. Since a magnetic, or fluid, or air, or spring base behave similarly, they are compressible in a vertical direction and will have negative results on dynamics at least.
Now, to address the vibration issue, which IS real, I believe that correctly engineered damping is the answer. If the vibrational modes of the turntable, base, and platform are properly addressed as a system, the rigid floor coupling can be maintained, and the vibration reduced sufficiently. This is the aim of some vibration control methods like sand tables and lead shot loading. Vibrations are dissipated in the small granules as heat, and the load path to the floor remains intact and coupled. My 2 cents.
Now, to address the vibration issue, which IS real, I believe that correctly engineered damping is the answer. If the vibrational modes of the turntable, base, and platform are properly addressed as a system, the rigid floor coupling can be maintained, and the vibration reduced sufficiently. This is the aim of some vibration control methods like sand tables and lead shot loading. Vibrations are dissipated in the small granules as heat, and the load path to the floor remains intact and coupled. My 2 cents.