Now this is of personal opinion but it has been put into practice through various means on WoW and Rift, and other games the like. I remember hearing/reading somewhere that one of the high ups in GW2 really enjoys memorable situations and having players go “Hey- you remember that time?!” with one time events. The problem you are currently facing and (in my opinion) you accidently caused upon yourselves is that you have angered a very large majority (including myself, so bias statement….) of your players by doing what you are currently having implimented. The method at which I mean is setting a time, date, and place for a one time- one go deal that happens once and thus far (from the two I have seen in my 53 days of play [at 400+ hours]) was a 5 second clip and a 2-5 hour (??) large event. The first had no significants, no real reward, and in my opinion was a great addition that you did. The second however you have made the graveous mistake.
What you implimented was a large event that had a significant reward (maybe it was just RNG but, hundreds of people have had great RNG in this case with it). Now, the players that were not able to attend due to the time at which your team has selected [stating it is when a large majority of activity is on which I can’t argue about] was unable to partake in the rewards as well as activity and missed out. This is a game and I don’t feel there should be a WoW raid time feel to it where “you make it or miss out on everything”. From a player perspective this was a very unfair implimentation. From a company perspective you can view it as your customers having a very unpleasant interaction from you and in most situations the reason most couldn’t make it was due to either work (which could imply paying customer buying gems) or other side of the world at graveyard hours. Of course that isn’t just the only two reasons possible but, having a negative impact could affect your profits earned from these players (this is simply my opinion so I have no hard facts here).
Now for the solution and my examples… As a long time gamer of WoW (no more) [Hopefully SOMEONE in your development community has played or you can look up some facts quick as I don’t wish to spend hours upon hours typing exactly what happened] I was there for AQ’s opening, The burning crusade’s launch, the lich king launch, cataclysm’s launch, and for Rift I was there for Greenscale’s release as well as the 2nd raid being released. In these situations though there was a ‘one time event’ that many players can attest to enjoying, remembering, and was a positive influence and shaped the community to being “Old timers telling stories of back in the day”. Why? The reason was the time and the method they were implimented. In all of the situations I listed most of the events lasted for roughly a week- some more. In every single method implimented that had some form of reward and some form of gain it gave every player a possibility to partake and enjoy in it.
In more detail lets look at the AQ event, there was a long run event that was similiar to what we had with the karka’s where there were rewards and we could do little things to get some benefit.