Yeah, but The Force is something that doesn't need any explanation at all.
If Lucas wanted to explain how a hyperdrive worked, then fine.
If Lucas wanted to explain how laser guns worked, fine.
If Lucas wanted to explain how a lightsbaer worked, then, er, wait, the crystal thing already has.
But The Force? It's like a religion. It IS a religion. Since when is religion ever proven with technology? The midichlorians thing just proves the Jedi religion as fact - it takes away the magic.
The one thing Lucas didn't need to/should never have tried to explain was The Force. It's just an aura, an energy, some people can use it, some can't.
It does explain why certain people are born with an affinity while some aren't - but it kinda makes the whole thing a bit, I dunno, "elitist". Like you can only be a Jedi if you have those stupid midichlorians telling you about it. I'm always a fan of "hard work achieves" - but what's the point if you are just born with these things, like a Jedi Prince or something.
So for me personally, I hope in Episode 3 the midichlorians turn out to be nothing more than intergalactic ringworm (and would explain why Anakin had so many being a slave and all), and The Force goes back to being about mythos and legend.