And, what should people do who have been playing for thirty years or more poorly using feel and vision? Of course, they should get checked out by an instructor, but they can find aim systems a boon, too, right?Feel and vision are more important and more fun — all the best players play on feel and vision.
Now, that has to be the silliest thing I've read on this place in a long time.

Number 1: Ask Darren about that. It's his words you quoted.
Number 2: A player who has been at the game for more than 30 years and still plays poorly probably has a lot worse problems than aim. Assuming that he has good fundamentals and a straight and consistant stroke, if he can't aim good enough to make balls after all those years he is obviously completely blind.
More likely, though, he doesn't have good fundamentals at all, and most likely has major issues with his stroke. Fix those things and come back to me when he is done and we'll see how much he needs an aiming system.
Such a player also obviously has no cue ball, and that has nothing to do with aim, it has to do with stroke. If he had great CB control and understood patterns well and knew how to stay in line and how to get back in line in order to run out, he wouldn't even need to aim that well because most of his shots would be ducks. It's really hard to play poorly if you get perfect shape every time.
He probably lacks a good break as well. You can't have a good break with a weak stroke. Fundamentals again.
You seem to be missing the point Daz is making. Of course, you have to aim the shot, that's a given. But get your priorities straight and concentrate on the foundation of the game, and not on esoteric aiming systems that take a lot of time to learn and don't bring any success at all unless your fundamentals are very sound in the first place.