Midichlorians don't explain the Force. They explain Force sensitivity, or why some people are Jedi material and some aren't. If they demystify the issue of Force sensitivity, that's fine with me. I'd rather have Force sensitivity explained in this way, as opposed to some people having it "just because". And we already knew from ROTJ that Force sensitivity can be passed down hereditarily in a bloodline, so midichlorians just provide specifics on how this happens.