The major argument in favor of making the OOC planning of Hell trips okay (like it was before, apparently) the complexity of organizing the trip.
The way I see it, there are three major general problems:
1) The group itself. You need certain classes, and in some cases, certain builds.
2) You need everyone to login and/or be available to begin at the same time.
3) You need everyone to be able and willing to play for an extended period of time.
Beyond that, you need a competent leader and you need to establish the fact that a certain person is "the leader".
Optionally, but a good idea, you need to farm some items to make things go faster.
I admit I've never tried to orchestrate a Hell trip. I've been on a handful of Hell trips, but never as a leader or as the person who suggested the trip in the first place. But...
It seems like all of these issues should be easily dealt with IC, given time. While I agree it's very unlikely that you're going to fight a suitable group of hero-level characters who are all compatible (allowed to group within RP restrictions), it seems like that can be solved by writing a note that advertises the intent to begin Hell expeditions far into the future. So you send a note to all with some RP bullshit about how the Sultan or Empress or whatever wishes to reap the treasures of the Inferno and will be financing a number of trips into the Inferno in the coming ("gods time") weeks. You could maintain a list of "interested parties" and track their progress. Yeah, you'd have to hope enough competent people express interest and actually level up the characters they make, but it could all be managed and monitored IC. The leader would basically be in charge of keep tabs of which key members are coming up through the ranks, what their skill level is, etc., and basically recruiting a team over time.
No fucking shit this is going to take much longer than planning it OOC, and it's quite a bit riskier since you don't know who is going to respond, who will follow through, and if you'll get all the pieces you need. If it worked, however, give you a glimmer of hope of seriously exploring Hell without the risk of getting clubbed with the Deny Stick.
Soo.. is that level of effort acceptable to anyone?
Or fuck that, plan it OOC?
Or fuck both those dumb ideas, Hell can kiss your dick?