I have come rather late to multi-crew aircraft, after about 11,000 hours of mostly single-pilot operation with a lot of two-crew in single-pilot types (Twin Otter, King Air) thrown in.
The LOFT sessions with some rather minor failure that requires me to work through CRM issues are far more challenging than just poling around on one engine with no autopilot and half the systems dead. I know how to fly the airplane; what I have to work at is working productively with that guy in the other seat.
We had a session with an electrical failure that meant the man in the right seat had to fly while the man in the left (in command) was left with almost nothing to work with (dead displays, no comms, no intercom). That was a real eye-opener. No dramas, just a lot of quiet pressure to come up with a solution.
Working through an MEL, following SOPs and figuring out how to complete the trip legally and safely is definitely worthwhile training in my opinion, and something that should be done in the sim and not in the classroom. Maybe it's only 10% handling and 90% procedures but the pressure only comes on in the sim, and handling the pressure is what I need to practise.