OMG!!! I so agree with you. I hated that Jim had to die and become Sam. It was a really stupid idea, and it can get sort of confusing. I always forget now that Jim is Sam because they never talk about it any más in the 5th season, which i am totally glad. I think they probably were running out of ideas , so they decided to use this really stupid one. I wish they never had did it.
I think they decided to do that story line to get más viewers (shake things up a bit). My friend was watching the mostrar w/ me and was complaining that its the same thing over and over. Melinda sees a ghost and helps it mover on. But when Jim died, my friend was totally obsessed w/ the mostrar again. Maybe thats why they did it....
It was stupid. They only did it for better ratings and más viewers. And now, the whole Sam thing is forgotten like it never happened. Which, I am happy about of course.