Does raising speaker cables off the floor really make a big difference?

Part of the problem in my situation is that power cords and speaker cables are all lying together in a small area. I don't have the floor space to separate them. 

LOL

Makes it easier when sweeping the floor in my listening room.

Yes, at very least it keeps your cables clean, and makes it easier to clean the floor.

"...interacts with the photons traveling down the cable dielectric..." That statement alone tells you all you need to know. Sorry, but photons don't travel down the dielectric. Not in our universe, anyway.