I like FirstAngelus' point that SW is fantasy with spaceships, not sci-fi. I'd never thought of it like that. I'm sure that idea's been around the internet, but I don't follow Star Wars very closely. I only saw it 3 times in the theater in 1977, so you can tell I'm not really dedicated.
Midichlorians were a attempt at a story convention which is very satisfying for the audience/reader when done properly: explaining and providing a reason for something curious the audience has already accepted. However, the Force didn't need an emperical explanation. The story would've been better without any attempt to explain.
And Miss Twilight, not to jack your thread, but you left out the supervillain of Eps 1-3: special effects. To borrow from Jurrasic Park, "The were so busy thinking about whether they could, they didn't stop to think if they should." The moments that should be the greatest and most tense (such as lightsaber battels) are usually ruined by 2,000 cgi soldiers storming the background. Ep 4 was character-driven and the one-on-one face-off between Vader and Obi-wan would have been much less potent if hives of stormtroopers had been scampering across multiple levels of the background. Nope, it's just me and you in this tunnel Vader. And if you strike me down, I shall become more powerful than you can imagine.