Haha idk who said that, but its so true.
But to be honest, any MMO is predictable, it just lacks the randomness. I think one solution may be to design dungeons randomly, and balance professions correctly (i.e you dont just need a crat+doc to do everything). Everytime you go into an instance, the boss' toolset changes. It could simply be a set of 5 powers, and you dont know what will come up. They could even add a new toolset each month or so. We get more powerful, why shouldnt the dustbrigade?
So, maybe one day you go inside the machine, and now aune is fearing, hope you brought a keeper with you. The next she is casting some nasty debuffs which she needs to be NSD or drained in order to stop. In another, she might hit really fast and really hard, but have low AR, making AR drains and an evade based tank crucial here. Another she could have a huge reflect, in which an engis -reflect aura, a doctors epsilon purge, NT nukes, or a trader (BR work in pvm?) to attack her.
The idea is you make a team, then you go in, but you dont know what to expect. So sometimes it might be easy, because you got the right team, other times you might have to think a little or focus a little harder.
Now ofc, instead of inviting MPs or keepers or traders when necessary, the team would rather reform until they get the boss-type they want. Or they would have just two people go in, then find out what professions they need. One way around this would be to force players to complete it. They cant do that instance again for a long time unless they do it with a subset of the original team (but NOT a superset). but this would really cause more anger than anything, unfortunately.