I think it's just run it's course and the attitude of the board members in the past.
I think the fact that the DIs, DIIs, and RRCs are so old that folks just don't have them anymore is a major factor. A lot of people upgraded to import 90s and 110s and a lot of the attitudes have changed. There are a bunch of people that simply think they are better than others because they have a "Defender".
If you're just into the brand and wheeling and getting together with friends it's great. I feel like these trucks have been around for a while now and the newer LR3-4-5, and RRS, and big l322s are just too new, expensive, and not offroad friendly. Th e guys that are still wheeling the older vehicles have their niche groups that they hang out with. A lot of those used to use the big events as get togethers, but with nothing new and comparable from the brand a lot of those desires and motivations have dwindled.
Nobody new is buying a used DI etc. The used Rover market is all import 90s and 110s now. These aren't guys who were all previous disco owners, some are, most arent. Even the imports are outrageously priced and the mentality of owners is different. Instead of caring about offroad mods and upgrades with purpose people care about paintjobs, wheel part numbers, seats, and other parts that most people used to rip out of their trucks.
Then you have the drama from ROAV in years past. I can't speak to most of it since I went to to MARs, 06 and 08. But 06 was very different than 08 even.
Not to mention, who can afford an event if you're paying $6500 in parts just to replace a tired 25-30 year old engine with a 5-10 year newer 200 or 300tdi that you realize isn't even that good and you end up selling your truck at a loss after 3 months of ownership?