Allow me to revise my previous post a bit. The fundamental question I was asking was:
“Is it a good use of designer resources to specifically construct one-time events (in MMOs)?”
The traditional sort of knee-jerk response would probably be “Yes.” My answer is No.
A one-time event is essentially the most extreme example of planned obsolescence in MMOs. If you get upset at the idea that nobody does Tier N content when Tier N+1 is released, then you should be grabbing pitchforks at the very mention of one-time events. Were you upset when ToC made Ulduar irrelevant? Were you sad when Cataclysm redesigned the entire leveling experience, including removing your favorite quests? Do you support attunements as a means to make all raids relevant through the duration of an expansion? Are you sad about how fast leveling has gotten in WoW, or how many dungeons are being “wasted?” If you answered Yes to any of those questions and yet still enjoy the idea of the AQ gate opening just the one time ever, then you have some serious cognitive dissonance going on.
A raid being rendered moot by the next patch’s 5m heroics is just another form of planned obsolescence; it is another form of one-time events, same as the leveling speed changing, dungeons becoming empty, and so on. The only difference is one of duration, e.g. months/years versus an hour on a Sunday afternoon.
There is, however, an important distinction to make here.
When ToC made Ulduar irrelevant, Ulduar still existed. In fact, you can still zone into Ulduar today and go have fun. Will it be the same experience as it was when it was the new hotness? Of course not – you can never cross the same river twice. The difficulty changed quite a bit following the months of its release, to say nothing of the changing abilities of players, the higher level cap, and so on. But fundamentally the place is still there and still capable of generating new memories. The planned obsolescence was social in nature, not structural. Blizzard did not simply remove the raid portal, or leave all the bosses dead. Few people wanted to do Ulduar after ToC was released because better gear was available elsewhere, they had gotten their fill of Ulduar content, they wanted to tackle new challenges, or whatever.
This brings me to a smaller point I was trying to make yesterday: social obsolescence happens naturally, automatically, and inevitably. If ToC was released with just sidegrades available, there still would have been fewer people raiding Ulduar; the exodus might not have been as abrupt, but it still would have occurred. Even in horizontal-progression games, you do not see an evenly distributed population. People generally crave novelty, and will mob whatever new content is introduced, leaving barren ghost towns in their wake. Nobody cares that you have got the Kingslayer title yesterday.
And so now we have arrived at my larger assertion: making events only occur once adds little to nothing to the experience.
Liore and Syl in the previous comments said that the AQ opening would have been less epic/less people would have showed up if it were repeatable. Based on what? Did those people know, for sure, that the gong would never be struck again? Would the significance of the first opening have been diminished in any real way if the event was available the very next year? Or weeks later? I have a hard time believing that could be the case, because Firsts are always special. Neil Armstrong is the first human to step on the moon; his accomplishment is in no way diminished by the fact eleven other dudes have also stepped on the moon. Have you heard of Eugene Cernan or Harrison Schmitt? Those are the last two people to have rung the gong on the moon, so to speak, but no one really cares. Neil still is/was the man.
Ultimately, to me, it comes down to a question of where best to utilize limited designer resources. When new raids and dungeons are released, there is always a special moment attached to it. A camaraderie that exists as thousands and thousands of players try something for the first time, race to the top, and otherwise share an experience. Undoubtedly that is the same goal of one-time events, to evoke those same feelings and perhaps pretend that this is a game world that is always changing (at 12:00 PM Pacific Time/19:00 GMT this Sunday only). The difference is that with the latter, the content is thereafter removed, generating no new experiences, no new memories, and no lasting history beyond the recollections of an ever-dwindling veteran playerbase.
I want game worlds to get bigger by having more things in them, not less, and not temporary things. Designers should stick with making the tools and toys; let the players bring the dynamic themselves.
And if you need something to only happen once to enjoy it the most, 1) I feel bad for you, and 2) the first time only happens once already. Enjoy the feeling as it lasts… don’t just take the ball and go home.