Amen, Old Smokey
I said the same in my post (not so brilliantly, however) and was accused of repeating rolljoe's post, though I cant' see why.
To the original post:
I prefer to consider the airspeed indicator as a dynamic pressure indicator.
EAS is not an airspeed. As a matter of fact is not a speed at all. TAS is the speed of the airplane relative to the air mass. Ground speed is the speed of the airplane relative to the ground. And EAS is the speed relative to... nothing. It is the speed that an airplane would have in the ISA at sea level if it had the same dynamic pressure that the airplane has.
All aerodynamic forces depend on dynamic pressure. That's why we don't refer to TAS when flying, except for navigation purposes. We use IAS, which is the closest to EAS that we have available.
When compressibility effects become noticeable and affect limitations and performance, dynamic pressure alone will not determine the aerodynamic behaviour of the airplane. Since Mach number is an indicator of compressibility, we will have to refer to it when it becomes high enough.
In civil airplanes this occurs at high levels. In military jets it can occur at sea level, where they have to be careful with both dynamic pressure and compressibility effects.
Hope this way of looking at this speeds thing helps.