Gentoras, that is no way correct about midwicket. It isn't often guarded because that is generally a spot a bad ball is put away. Anything full-ish and on the stumps is an invitation to punch through this area. Alternatively, if your bowling for LBW vs a guy who has a tendency to fall over to the offside around a planted front foot, you will generally have midwicket, square leg and mid-on if, as you are going to offer scoring opportunities in this area.
See Kallis talking about it:
Jacques Kallis gives Sky Cricket batting masterclass in The Zone on The Verdict | News
Kallis on hitting leg-side
"I knew I had to be very well-balanced not to miss and get out lbw or bowled. I had to get my head and eyes parallel to the stumps, be nice and still, and really concentrate so that when the ball was straight, I was over my front foot to allow me to hit it. If you start looking to hit it through square-leg or mid-wicket too early, you’re going to get into trouble, come across the ball and try to hit it with half a bat. The odds aren’t in your favour. First you’ve got to look to hit it as straight as possible and then if the ball does carry on drifting in, hit it through mid-wicket. You need to make sure you’re well-balanced for that."