On the face of it, something that reflects both length as well as girth initially sounds like an ideal system. However, it seems like differing sizes could also yield identical results, where a girthy cock lacking length could give the same CQ as a long cock lacking girth. Granted, since we all have the inherent flaws of all humans, we would all have a knee-jerk positive response to large numbers regardless of the factors used to arrive at those numbers, but those prone to seeking thickness specifically, or length specifically, would then have to subsequently ask for the length and diameter in order to know what they wanted to know in the first place, which makes CQ irrelevant as well as a speedbump in the process, an aggravating misdirection down a side path when we wanted to stay on the main road. Personally I don't see it as much of a hassle to deal with two numbers, which when I see them they automatically give me a good idea of the dimensions. The fellow who has the 13.75 x 8 dimensions, seeing those two numbers, lets me know exactly his length, and exactly his girth (both admirably huge), without having to do any math. Whereas the CQ 637, while it's a huge number also, gives me no idea of what exactly he's packing, even though is sounds like a flagpole I can't even begin to visualize it.
Prediction? The concept of having one magical number that reflects both dimensions will not even begin to catch on, for the exact reasons I stated above. Sorry.
Now if you were to devise with a nomenclature that reflects both, say where the first number or numbers are the length and the subsequent numbers are the diameter then maybe that could happen. The fellow with the dimensions I quoted earlier might then be 13758, and we could kind of logically figure that out knowing the 75 was probably a .75 and the last number logically being an 8 rather than the illogic of a 58 or .58, as long as everyone knew to measure to the nearest .25 then perhaps....
But it all seems like chinese math to combat something that wasn't really a problem to begin with, like using a shotgun to kill a fly. The old "length by diameter" will probably have to suffice for the next millenia or so.
I do appreciate higher thinking though. It just probably won't work in this instance. KISS = keep it simple ......