I despise the USTA on many levels, and they do control the League rules. However, as far as tournaments go, they are not the ones that determine the scoring format. Even in a sanctioned tournament, the tournament director is given control over this.
I completely understand what Craig is talking about regarding the loss of the "fitness" factor without third sets. I was playing tons of tournaments from '95 to '01, and many of my best wins came from third set comebacks where I outlasted my opponent. However, I took a 4 year break from the game, and when I returned in '05, I was shocked with the prevalence of the super-tiebreaker. Never-the-less, I have now bought into the benefits of it:
1.) There is an NTRP grand prix tournament series that a local club puts on. They used to play out the third set, and the tournament schedule was always WAYYYYY off. For instance, if your match was scheduled for 3:00 on Saturday, it was pretty likely that you wouldn't really get on the court until around 5:30 or 6:00 because of all the matches going overtime. The super-tiebreak has cleared this problem up, and that tournament series now plays fairly close to schedule... even as participation has increased by 50% or more.
2.) With the introduction of super-tiebreaks in tournaments, more matches can be scheduled and still keep the tournament moving. This means that you are more likely to have consolation events. I have played 17 tournaments so far this year, and all but 1 that had the super-tiebreak had consolations also... and only 1 that played with full regular scoring had consolations. Consolations are a big deal to me, especially if I'm going to pay $30 or more for an entry fee (which is the average I've paid this year) and travel a long way to play.
3.) As discussed briefly in another thread, I would rather play regular scoring for two sets and then have a super-tiebreaker for the third than have no-ad scoring for best of three. If, as some of you say, the super-tiebreak is a "coin flip", then what do you call no-ad scoring? (I played the #1 seed in a 35 & Over tournament earlier this year that was using no-ad scoring. This guy was 10X better than me, but we had a really close first set because I won 4 games on the no-ad point... and in all of those points, I either shanked a ball that landed in by luck, or I hit the net and had the ball dribble over for a winner. To me, this wasn't "earning" the match as much as getting lucky. With regular scoring, I probably only would have won 1 of those games.)
4.) As much as the full third set is about fitness, the super-tiebreak format is about focus and concentration. When I know I'm in a tournament with that format, I really try to win all of my matches in straight sets so I don't tempt fate with the breaker. If I do get into a super-tiebreak, it's all about holding serve and getting "mini-breaks" on the return so that I can take care of business. To me, this mentality leads to sharper tennis.