Both IM1 and IM2 were a mess and yeah Rourke was pissed that his character wasn't fleshed out and that everything he wanted to do was shut down.
Jeff Bridges was actually talking about his IM1 experience again around SDCC this year, everyone behind the scene just seems happy they finished that film and really no wonder why IM1 is the only one that's been actually good. I am not sure about IM3 but IM2 was just as messy if not more.
"We were so fortunate to have Robert and that team, and also Jon Favreau, both those guys are incredible actors and improvisers. And that movie was so much fun to make. It was unusual because it was very expensive, close to $200 million or something, and you would think that a movie that had that high a budget, they would have had their script tighter. But that was not the case. And we would very often find ourselves, at the beginning of the day, going into our trailers with little tape recorders with the suits from Marvel & Jon & Robert, and we would try to come up with what we were going to shoot that day! We would trade parts, I would play his part, or he would play my part, Favreau would be calling up writer friends of his, and meanwhile the crew is tapping their foot, waiting for us to come back to work. That was very frustrating for me, because I like to be very prepared and let it go in front of the camera, so that you know your lines and stuff, until I made a small inner adjustment that was: realizing we were making a $200 million dollar student film. And just to relax and have fun, do your best, don't worry too much, and I think that the film came out terrifically! And again, that's largely because we had Robert and Jon onboard."
They truly did get lucky because if IM1 had bombed, there would be a big chance that Marvel wouldn't be where they are at today.