Here is a link to a very interesting 2011 trackman study done by a a club pro comparing a Balata, a Professional, an early ProV1, and a recent 2011 ProV1. (And also an early ProV1x, although without all the numbers.) Swing speed of the golfer, 110 mph.
http://www.andrewricegolf.com/tag/tour-balata/More complete stats are available at the link but here are the top line numbers.
Balata 261.6 yds
Professional 262.1 yds
Pro V1-392 286.4 yds
Pro V1 298.4 yds
ProV1x -392 307.3 yds
This golfer hit the old model ProV1x about 45 yards beyond the Balata and the Professional. It is not apples to apples, but this beats the heck out of the 3 yard gain the average golfers picked up in that R&A study.
The most surprising number to me is the big gain in the newer ProV1 over the older one. This might support my hunch that over the years the ProV1 has become more like the ProV1x.
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As for your questions . . .
Of course average players are incompetent, inconsistent, etc. Of course they are all over the club face. That is why they suck. It is also part of the reason the new technology (including optimization) doesn't do them much good. Swing speed is the other part. Both parts have increased the gap between good and bad, and both are technology driven.
As for optimization, optimization isn't going to help them because they stink at consistently striking the ball. You need consistency to optimize. Also they lack the physical tools to take advantage of things like low spin balls, and advanced shafts, etc.
No I don't think hacks should have been able to hit the ProV1x 20 yards longer. That'd be horrible! I don't think anyone should be able to hit the ProV1x, period.
Average players have always been horrible and they likely always will be. But as horrible as they are, for about a century the proportionality of the game (and therefore the architecture) was in balance between long and short. Now it isn't. It doesn't matter why they suck, what matters is that 1) the overall distance does not render courses obsolete, and 2) some sort of workable proportionality is preserved between long and short.