But for some reason, when I try to come up with a "plot" for my players, I just fizzle out. (I actually have the same issue with creative writing.) D&D, Star Wars, Call of Cthulhu, superhero games....whatever the system or genre, I'm just not able to generate cool ideas or plots for my players to game through.
I'd like to be able to wean myself off pre-published adventures (with Goodman Games' products the exception, of course

Part of the issue is that I don't know how to craft "good" villains. I'm not socially awkward, but I just simply don't understand what makes an evil person tick--their motivation--in such a way that I can create a plot from it. (Does that mean I'm evil...?!)
The stories I create tend to be...elaborate, to the point of being overcomplicated. I think in the abstract rather than the concrete.
I have, in the past, tried to convert current events into fantasy plots....they end up coming across as...well, current events with the serial numbers filed off.

I'm also certain that I have a high internal expectation--possibly a false expectation--that my plots have to be original and new and fresh. That puts a huge weight of pressure on me. I absolutely dread cliché, over-used plot seeds....I absolutely must put a spin or twist on any so-called normal storyline...but have little ability to generate new ones.
I have no problem using plots from things my players have never seen / read, but that's few and far between...despite being on the young side, my players are shockingly well-read and most watch a fair amount of TV. I try to steal ideas from media that is typically too old for my players to have seen or read, especially as I'm an old fart myself.

So, maybe the developers can help: what helps generate ideas for your plots? How do you "fantasy up" current events in such a way that they're less recognizable as current events? Is there anything that makes converting stories/comics/TV shows into RPGs easier? And how do you develop "cool" opponents for players?