Tammy, I would not go quite that far. I think you can make a case, though, that things be rated for their use.
Ordinary plugs, and receptacles, are not rated as a disconnecting means for larger loads and higher voltages. There are exceptions; one company ("Meltric" I think) makes such connectors as their primary business. There are others that incorporate a switch in the receptacle, so you actually 'turn it off' as you begin to remove the plug.
Looking at the code, we see that cords and plugs are allowed to be the disconnecting means for only the smalest of motors. This does not mean you cannot use cords on larger stuff; it only means that there must be an additional disconnecting means.
So, using your air conditioner example, I would say that the receptacle would need to have a switch controlling it.
