One thing it doesn't do is make the lawyers richer. The CPS are on salaries. The barrister on either side only gets paid for a trial when it starts and there will be no extra fees claimable for written opinions between the case being taken out of the list and it starting because they're won't be any. If the case is listed and the barrister has to attend but it doesn't start, he or she gets only a nominal fee, which barely covers his costs and is nothing compared to what he gets for starting. The solicitor likewise earns no more.
The usual reason for a case being taken out is simply that the list office finds that it hasn't got enough time for it to be heard, usually because the office has put too many effective cases in the list, or cases on are over- running the expected time. Being told at 4.30 the night before, on the appearance of the list for the next day, that the case is not listed, is the bane of lawyers' lives, never mind the poor witnesses'. In itself, the non-listing is not sinister. If the list office were told that the prosecution wasn't ready, they'd be inclined to list it anyway, so that the prosecution could make their excuses and a proper enquiry made and, in the absence of good reason, the case proceed. It might not, but the judge might say it should.