The fact that solutions are being proposed to a problem that can be so trivially shown not to exists calls into question the real motives of the people pushing said solutions.
I believe their motive is to try to convince those who want to cripple Bitcoin to a 1Mb block size limit that such crippling is not a good idea...
Have there been good arguments against a dynamic cap?
I used to support such idea, until I realize that a dynamic cap implies in an arbitrary formula, and that's an attempt to guess subjective demands and unpredictable supplies. It's impossible, and fortunately, not necessary.