Hey teropa,
I just started an FAA IR and there's no comparison between sitting at a nice comfy desk playing Flight Sim, and sitting in a real plane (172 in my case) desparately trying to concentrate hard enough to
1. Scan the instruments
2. Interpret the instruments
3. Control the aircraft
Here's an example, flying a simple approach style pattern, trying to work a timer, and read the instructions off a piece of paper was enough to cause my scan to break for just a few seconds -- hardly exceptional for a begining IR pilot -- and in that time, the aircraft got off heading, pitched down enough to gain 10 knots, and I had to work pretty hard to get it all back in shape.
Now try talking on the radio, talking with people around you, actually looking at a real, dirty and in the life flight deck, and doing all this at 3 or 4 times the speed of what I can barely cope with in a 172.
This is the bread and butter of professional pilots.
I don't think I'd be volunteering to take the controls of that aircraft if there were other pax on board ...