As someone who does new product research for a living, I think this can be a useful exercise. I imagine that few if any high-end companies do any serious market research. Most get their feeback informally from the channel and, of course, from their customers, as it should be. But just like this, it's qualitative.
Here are some of my thoughts:
More CDPs should have accomodations for hard-drive based systems, so a digital input to access the DAC. USB is good, but S/PDIF is the first choice I think.
More standardization of spade connector sizes. I keep running into speakers that will not easily accept the spades on my speaker cables.
Some facility on components for "grabbing" the power cord IEC connector and holding it tight.
Better labeling of inputs and outputs and switches on the backs of components: bright lettering that is sufficiently large to read from a angle and in less than ideal light.
More attention to fine gradations of attentuation at the low end of the volume scale. Very frustrating to have a system you can not turn down enough (for very low-level listening) or set to the level you truly want.