Garland,
I saw a study that says average golfers hit only 5 to 15 good shots a game. If they hit less than 5, they simply quit. If a newbie has a few rounds where he gets somewhere close to 15 good shots a game, he becomes a lifelong golfer.
Not sure if "good" means airborne, or if it means hit a fw or green, or made a putt over a few feet long. I suspect that in addtion to hitting it nicely, there has to be some golfing reward, like a GIR. Thus, I would say that yes, hitting greens via shorter courses (and using shorter clubs) is a big boost to golf participation.
Think about it - the par 4 is the dominant hole because the tee shot sets it up and the approach shot is the gravy. Par 5's are weaker (unless reachable in two) mostly because that middle shot inherently has less interest than the other two. If we add 14 non interseting shots per round via only length, can that make a golfer happy?
I have gotten feedback from women on my program of new shorter tees at 4300 yards or so. At that length, one decent female player told me that she is "thrilled at being able to reach the four par 3's with irons (each under 100 yards, but she thought 100 should be the minimum) and just FIVE longer holes, for 9 total. Just think how thrilled she - or most golfers of either sex - would be if every good tee shot was rewarded with a reasonable shot at the green, rather than an opportunity to advance it once or twice before having a real "golfy" shot, i.e., an approach to the green with some interest?
Not sure it has all that much to do with handicap as much as hitting golf shots that matter to score, which is slightly different.