Prior to my retirement form the marine industry, over the years I rep'd for North, U/K, and most recently Quantum. Sadly the odds of my attending a Class OD event are likely slim to none so I really don't have a dog in this hunt but decided I would offer up a few thoughts on this from a third party who has also been active in other classes.
The ultimate concern that seems to oppose the change to laminate mainsails is concerns of cost and to a lesser extent longevity (ultimately another argument about costs). On the costs theme it should be noted that not all laminate sails are created equally. Recent advancements in sailcloth design mean that laminate sails can now take advantage of less labour intensive cross-cut construction methods, that when combined with offshore production (further taking advantage of cheaper labour) means that laminate mainsails can be had at price points virtually on par with conventional Dacron mainsails (it should also be noted that Dacron is a fairly premium material and has not fallen in price as many laminate cloths have) As far as longevity, both laminate and Dacron also have a comparable competitive lifespan although ultimately it will take Dacron longer to self destruct but that is really a different discussion.
With all due respect to the OD class stalwarts, in my humble opinion, I would submit that people are no longer buying the J/30 for "class racing" Most, like myself, are buying the J/30 for the comfort of the design and the fact that the boat can still be competitively raced, and for the vast majority of us, competitive racing is going to involve PHRF, that is simply a reality. There are very, very few boats campaigning in PHRF that do not take advantage of the performance and reduced weight of laminate sails, more so as the prices have come down on par with Dacron. I do not believe there is anyone buying a J/30 because if they were to race class, the can save a few dollars by not having to replace a Dacron mainsail after it is 5 years old. Further the poll shows the majority race PHRF and there are greater cost efficiencies if you can have only ONE competitive mainsail as part of your program and be able to race PHRF and Class with that mainsail. Some class members have talked about having a "class Dacron" mainsail rolled up in the basement just for class events. This in itself seems somewhat wasteful.
From my perspective it just seems to make sense to try and streamline a competitive PHRF inventory with a Class legal inventory. The alternative, as you have already heard from some, is that exceptions may end up getting made if it means getting a few more boats on the line. I will say that if the costs of exotic sails were still on par with building a tri-radial Kevlar mainsail (still a very pricey option) I would feel differently, however most every sail maker now has an affordable laminate product that offers a competitive lifespan on par with Dacron. Just my .02