I could probably respond with an equally long editorial (and I may at some point), but for now I'll just say that John's piece made some valid points. I'll also add, however, that I don't quite agree with everything. Yes, one's modeling comes first ahead of any need to be "taken seriously;" that said, it might help grow the market if we saw more serious work being done in Z. It's a chicken-egg conundrum with no simple solution.
As for "where are the switchers," the typical American switcher in Z presents some tough technical challenges to overcome, an issue to which I'm sure Joe can attest. People might be tempted to say, well, Märklin has done that 0-6-0 since forever, why can't we have some diesel switchers? It's much easier to make a short, stocky rigid-axle loco than a slender one with trucks. Consider the $500 SW1/9/900 from Huet-Trains in France: the center two axles are rigidly-mounted, the trucks do not swivel, only four wheels are powered, and only six have electrical pick up. Likely the first affordable switchers we'll see will be newer, chunkier units such as the MP15, which can be reliably powered without having to develop some new cutting-edge mechanism. If I can ever find the time, I'm still going to finish the shell for the MP15 I started way back when.