Agreed - the two nitrox options that NAUI offers is a compromise made for marketing purposes. NAUI did not like seeing so many potential students pass from taking a NAUI class because the requirements for Agency XY or Z were simpler. Thus was born the no-dive recognition option. Take the recognition class and a person still gets a card, and still can obtain a nitrox fill at a fill station or rent a nitrox cylinder.
So, why do the mossbacks think its reasonable to require dives in a nitrox class? Its not the math that counts - heck, my calculator doesn't actually work under water, so that's not going to help. And my inflator button works the same whether 21% or 40% come out of my cylinder. But diving requires judgement calls, and nitrox diving requires additional judgements. We all know that there are cyber divers, and textbook divers, and classroom divers who can do the math, physics and other knowledge-based stuff, but who do not make good desicions around (or under) water. I teach a fair amount of nitrox, always require two dives, and I have yet to end a class where the required dives did not result in some good learning.
Example: You've prepared a mix for an 85' dive. The dive boat gets to the site and there are two fishing boats tied in. Captain of the dive op scratches that site, and moves to a deeper wreck with a bottom of 135', but with the deck at 105, the wheelhouse at 95' and some light structure starting at 60. Maybe Ol Mossback would see the issues and opportunities right away for this dive, but would the person who just completed her on-line or classroom-only recognition class be fully prepped to adjust the dive plan? What a great opportunity for an instructor to seize this teachable moment and lead some decision-making judgement calls. How many ways could this dive plan be altered on the fly (but before jumping in the water)? What risks would the new nitrox users face. Let's throw in issues involving currents and a host of other un-planned contingencies...
I've also used the required dives to help students fine tune their buoyancy, make adjustments to divers' weight requirements (and thus lower the workload), and help divers improve their air consumption so that the full benefits of nitrox become available. We've managed to sneak in a few new skills as well (deploying a blob, retrieving an anchor, etc) even tho they have nothing to do with nitrox. We sometimes forget that divers learn as they go - people aren't born with advanced dive skills. And folks will learn good and bad habits as they go. Instructors who are worth their spit should be trying to reduce the learning of bad habits, and increase their oportunitiies to teach good dive habits.
As for the class doing the nitrox dive in a 25' pond: If they don't know what the objective of a training dive is, they should get their money back. If the instructor didn't help them establish an objective, could we recall his/her instructor status please???