Ha, that is a good old chestnut that has not reared it's head for a long time! What you say is theoretically true and was certainly noticeable back in the days of your Olympus OM1 (
) but the quality of many good quality zooms these days is such that you would be hard pressed to tell whether a zoom had been used or not. The new Canon 70-200 L IS zoom is a match for almost anything prime or not for instance. The down side is that today's new materials and designs have made available 'all in one' zooms with incredibly wide zoom ranges which of course leads to too many design compromises and so quality definitely suffers. Same with 'kit' zooms which are built down to a price and will not match a 50mm prime at that focal length but does give versatility, That is the point of course, versatility. Two or three zoom lenses will cover an enormous range of focal lengths at a reasonable cost and are light enough to carry. A fixed focal length lens does not take a better picture if it is left at home because so many lenses are too heavy! Your last point of course has some validity but there are occasions when a zoom makes a shot possible where it would not otherwise be so because you can not move around or have not got the time to. One last point, smaller and lighter? At one focal length yes but not if you dial in all the focal lengths covered by the zoom. Horses for courses, I am lucky enough to use both zooms and a couple of fixed focal lengths (400mm and 100mm macro). There Alex that should help kick off the debate for others to join in.