To the original question - lighter and/or larger. That would be the easiest way to regulate and police.
To the question of skill - successful golf requires a whole set of skills, of which length is only one. How about distance control, sand shots, chipping, green reading, putting, spin control, trajectory control, shaping ability. No one, not even the greatest, were at the top of all skills (e.g. Nicklaus and short game, Tiger and driving accuracy). New technology has helped different skills - graphite enabling longer shafts and more distance, u-grooves improving spin out of the rough, anchored putters calming putting yips, higher moi yielding more forgiveness, etc. -each of these benefited different players in different ways.
Garland, vis-a-vis your frequent claims that the longer pros were given a ball that allowed them to hit it even longer and straighter, I give you the following examples to ponder - not that you ponder for long.
I took five long hitters from 1997 - Daly, Woods, Love III, Mickelson. and Couples - and looked at their distance gain by 2003. In order they gained 12, 5, 11, 22, and 9 yards. So, Mickelson was the only one who got an egregious distance gain. Then looking at each of their % of fairways hit comparing 1997 to 2003, the results were, in order, -5, -6, -3, -18, and -9. So, Mickelson paid a big price in the accuracy game for the large distance gain. The rest gained some distance and lost some accuracy. I would conclude based on this limited sample that, although there were distance gains attributable to the ball, there was an accuracy price to pay.
Jeff,
Re your statement "
So the long and short hitter distance gap grew (in absolute yards-not in %)", I'd offer the following chart from a couple of years ago. The bottom half shows the delta , in yards, between the Tour's longest and shortest hitter. It's been remarkably stable around 50 yards since 1991.