Well, in short, most of FFXI's events are based on the idea that a lot of people are participating.
Over the years, less and less people participate in these events.
Since the rewards are they same as last year, there's no reason to repeat the event if you've done it.
There's never anyone else participating either, for those who want to do it.
An example would be the current Feast of Swords, it takes a VERY LONG TIME to actually finish killing an Armor. They have way too much HP to do it solo, and as I said, nobody else is participating because they either already finished or simply don't care for events. Plus, most events don't provide any actual entertainment to make anyone want to just come out and do it with me for no reason.
Just saying, you're making tons of other changes due to the lack of player interest in things that require groups outside of end-game, why do all the events still suck?
I'd highly suggest making new events, remodeling old events, and giving out new rewards that are actually relevant. Or, you could take the lazy option and do things like giving the armors less HP.