I suppose that he's somehow easier to beat down with the lvl cap being at what, 85 now? And to answer your question, I'm pretty sure the reason don't want to beat him anymore is the logistic needed to kill him. Having people swapping jobs, coming back, gathering, buffing, going at him. For most of the shells I've done dynamis with, it required a lot of time, actually a lot of downtime waiting for other people. 10-15mins is not that long, I'd even say it's pretty good. It requires people knowing what they do and ready to be as fast as possible when it's time to go.
The other factor is the timer. If you got a lot of time, let's say 1h+ just for the kick. If you know, as a leader, that your group can kill him pretty fast and can continue farming without having the same group who changed to go change again, I'd go for it. You're losing 15-20mins of your time + the time to get to him. On the other hand, as a leader too, if you feel there is a chance that shit is gonna go haywire. Do you want to risk the time to get to him plus the time to change your people plus the possible chance of a wipe? It was not an easy guy to beat back in the days with a non-experienced group and even with the lvl cap raised, it's probably still a good contract to take up nowadays. Personnaly, if you got a well oiled machine on your hand, I'd do it, especially if people wants SL gears. And from what I read, it seems so lol.
It's just a matter of taking a decision to farm or to go for it. I'm not sure how much some AF2's are worth since a couple of patch but you need, as a leader, to consider everyone interest about AF2 or SL.I've learned that in the last couple of years, sorta.