At the risk of being accused of taking your "bait" again, let me give you another opinion. 

Bowling is an environmental game.  We all adapt to our environment, and the predominant environment for most league bowlers is a wet dry pattern typically referred to as the THS.  It is possible to develop a game that allows a person to average 200+ on such conditions without having the versatility to adjust to different patterns.   

Sport patterns with their flatter characteristic edge to edge have been around for almost 15 years now.  They are still not the predominant environment.  As an old geezer who still likes to bowl for money, I go out of my way to bowl on tournament patterns as much as possible.  As a result I find a lot of tournament patterns play as easy to the pocket as a THS.  I have probably given up a bit of carry on THS to maximize my game on tournament patterns.  Again, that is my environment, and it rewards me for the adaptions I have made. 

People bowl the best on what they are most accustomed to.  Most people would average higher in nationals if they got a steady diet of sport patterns in league.  Would some people quit the game.  Maybe, but not nearly as many as people think.  Would top league averages go down.  Sure, but again, not as much as people think.

Bottom line most people average a lot higher on house shots than sport patterns.  The best bowlers, a difference but not nearly as much.  USBC is designed to reward those bowlers. 

Just as an aside, the conditions today in nationals play like a house shot compared to what they were like from the mid 70's to the late 80's.  AMF HPL surface ushered in the high scoring era in nationals.  This forced them to soften up the shot a bit on Brunswick lanes.  Then the resin ball came in, and it opened up the shot to everyone who could find a way to the pocket.  I averaged about 195 for 6 trips to the ABC prior to 1988.  Over 210 for 20 trips since 1995.     

I believe what Bob is saying that if the current THS 230 bowled on sport conditions on a regular basis they would learn how to average higher than they currently do and eventually might average 215 or 220 on sport conditions.

Which might be true if everyone in the league learned how to break down lanes but since that probably isn't going to happen you are going to run into situations where conditions can become near impossible.

I think it is more fun bowling on flatter patterns of varying length.  However, I will admit that it is self serving.  I am more competitive on these patterns than on those that reward high revs and lots of hook. 

Here is a question I always ask.  If I can beat a guy on a flat short pattern, but he can beat me on a THS, who is better.  Unlike a lot of people I don't think there is anything wrong with a THS.  In fact I think it should be a tournament pattern right along with the sport patterns.  It just shouldn't be the only pattern people get to see if they want to get really good at the game.  When I learned to bowl in the stone age, there were lots of easy houses, and lots of tough houses.  However, even the easy ones played different.  On some I had to square up off the corner.  Others the track was so good at 15 board that it was hard to pull one high.  On these diverse conditions we had to learn how to throw a strong ball, but not at the expense of being able to line up and read the lanes 

The true test of bowling greatness has never been about style, but about versatility. 

I am in a league that uses the Nats patterns
however, we have 4 quarters to the league and 4 patterns
medium, short, long and then Nats
all 8 weeks
the thinking behind this is that you learn how to play different parts of the lane which in turn creates thinking about surface, lane play, ball choices, etc..
all good things that will make you better overall
im not sure i would want to be on the nats shot for a whole league season
i wouldn't want to use the same ball(s) every week