Pete, on the whole I tend to agree, but feel that etched work still has it's place, a good example would be cab side sheets, roofs and footplates, however resin castings for other areas are better, smoke box doors maybe even whole cylinder castings.
As a whole, I think the model railway scene needs to move forward and accept a more multimedia make up to the kits, much like the military scene does already. The hardest part I've found is finding a suitable adhesive to affix multimedia parts, which is probably why many prefer brass or white metal castings, simply from an adhesive choice and ease of use.
I also agree on kit updating, as you say, people demand more these days.