Late to the party here but my thoughts on pitching machines has changed over the years. My DD hated them so I also hated them. I finally figure out why she hated them and she has been a better hitter ever since.
Pitching machines teach one very very critical part of hitting. When you see the ball out of the hand, your step/load should already be out of the way. I see lots of kids trigger their swing at front foot contact, but they have to get the foot down so early they are essentially timing a pitch that hasn't even left the pitchers hand yet. Those kids are susceptible to off-speed or slow to catch up to fastballs.
You know those kids right away because they can't hit a speedy pitch from a pitching machine. They rely on the windup and since you don't have one, they look way out of whack. Get the step/load out of the way 'early' and all thats left is a small weight transfer and a the swing. Very easy to determine those kids on a machine.