he problems introduced should be operational and could include (but not be limited to) technical failure, operational requirements, weather related, passenger related, security induced etc and have side issues such as political (go/no go countries, FIR clearances), terrain, fuel, operational minima (MOA due winds, MDA, runway load and bearing limitations,etc), procedural (NATS track procedures for wx/technical).
These are all time wasting in a simulator. If as people claim, that simulator time is expensive and therefore subject to priority training, surely most of what I am reading above could be equally effective if conducted in a class room with a "facilitator". Leave simulator training for hands on regular practice of sequences that need real handling skills (not necessarily all button pressing) or those that cannot be safely completed in the real aircraft - after all, wasn't that why full motion simulators were designed in the first place?