The biggest thing that succession and community games have going for them that leads to the infamous insanity you always hear about is mainly the level of player involvement. I'm not talking about just that there are multiple people playing the same fort but that each person will have a dwarf that is their avatar. In most cases when I play a normal fortress things tend to run efficiently, with each dwarf being given what he needs and nothing more. I was the invisible overseer that ruled all and all that happened was under either my judgement or that of the RNG.
However in succession fortresses you aren't a formless overseer, you usually are one of the dwarves. In my first succession fort I ended up making a large dining room, bedroom, office, and tomb all for myself with everything that could be made of steel, made of it. Steel thrones, tables, and statues. A steel sarcophagus, chests and cabinets. All because I was the one that kicked steel production into high gear and I felt that I had earned the right to that steel covered room. That sort of thing rarely happens when a single person holds continuous sway over the fort.
There's also the fact that each player want's their turn to mean something. This makes them do crazy and irresponsible things that they wouldn't normally do, all for a chance to be able to have every player thereafter say, "Hey, Rentorian did that. Friggen moron." Each player hurries to make their superweapon, their monument, their spic tomb, even at the detriment to the for as a whole. Completly disregarding things like failsafes, safe working environments, and proper testing.
Community games don't have the same level of individual participation but as long as the person running the game is constantly taking input form the community, and possibly even making sure that each player's avatar does things that the person wants them to do, the same level of insanity can be achieved simply because the fort is once again being run by multiple individuals instead of just an invisible entity. Each with their own agenda that may or may not have the fort's best interests at heart.
All in all this has just been a long way of saying you don't have to force it. As long as you get people to participate the madness will build and build until either death or sheer awe at your creation is achieved.
With the awe followed shortly by death of course.