I understand what USBC was going for with the rule change. Back in the day, weight holes were used to make sure balls were legal. In more modern times, gurus like Mo figured out how to use them to drastically alter ball reaction. That wasn't what was originally intended, so USBC wanted to phase it out. Now, manufacturers are trying to figure out ways of designing cores that mimic weight holes without actually having to drill them. It's a back and forth that will continue.

Also, USBC was getting all kinds of heat about two-handers and how much of an advantage they have. As someone who dabbled in two-handed for a while, I can tell you that you still have to make shots in order to score. Well, at least on anything more than a walled up house shot that is. Anyhow, layouts like the triangle left things way too wide open under the old rules. As such, USBC changed things to make sure two-handers couldn't have six layouts in one ball or anything else like that.

It's kind of a damned if you do and damned if you don't situation. If they would've left things untouched, people would've continued complaining about that. Instead, they made the change, and people complain about it. In the end, people just like complaining. It's really that simple.

The USBC is pretty clear that all holes must be used during delivery.  They define delivery as the time the ball is in the possession of the bowler until they let go of it and put it into the lane.  Therefore, if the ball has a thumb hole it needs to have a thumb in it until the bowler releases it.

4a. Legal Delivery 
A delivery is made when the ball leaves the player’s possession and crosses the foul line into playing territory.

Is a bowling ball with a thumb hole thrown by a no-thumb or two-handed bowler legal?
A bowler who doesn’t use the thumb during a delivery cannot have a thumb hole, as it is  considered a balance hole. If the ball does, it is illegal and games are subject to forfeiture. All holes drilled must be used for gripping purposes on every delivery.

The balance hole argument makes no sense.  Doesn't matter if the bowler uses their thumb or not.  In the case of a no-thumb bowler with a thumb hole and a thumb-in bowler, both balls will have [in most cases] three holes rolling down the lane.  A thumb hole for a no-thumb bowler does nothing dynamically during delivery.

The rule is what the rule is, but it really makes no sense.  Now if the no-thumb bowler has a hole in the P1, P2, P3, or P4 position and claims it is a thumb hole that is an entirely different matter.

kiefenstien - Did he use his thumb in the Doubles/Singles or just wasn't caught? My guess is he just didn't get caught.

I really don't know if the rule makes a difference at that level but the rules should be enforced. If not who decides which rules to ignore.

I was bowling state a few years back and they made an announcement before practice started that you were only to take one shot and leave the approach and you should not reset to get a full rack of pins. A bowler on the other team reset every time he didn't have a full rack and wouldn't stop when called out on it. The officials refused to do anything to the bowler and he he got his way. That didn't set real  well with me.

Well that's one of the dumbest rules I've ever heard. Carry is the whole game, you can put a blind fold on and hit the headpin. If I'm in line behind someone who sucks you're basically telling me I don't get any practice here.