Sometimes I think shooting in M is overrated. I agree there are situations where you should, and knowing how the settings work is always good, but for the most part, the auto settings do a decent job. I'm a big fan of AV, personally. I set my ISO and aperture, and let it do the rest of the work. Of course, I know that if my SS is too low I need to change one of the other settings so that I get a decent shot, but I don't need to be in Manual to get it.
So, even if you never want to shoot fully manual, you'd benefit from learning how exposure works. But at the same time, don't get all hung up on it, because a good portion of the time, it wouldn't make a whole ton of difference either way.