Hah! In the inmortal words of Big John McCarthy: "Let's get it on!"
Dude, you're right, you're aiming at the same spot. But the trick is hitting it when the bag's there!
Granted, once you get the rhythm it's more a matter of maintining it. I've gotten to the point where I can take my eyes off the bag for a time and not miss... But only for so long. You need to coordinate hand with eye. I'll grant you it gets easier with time. Then again, that's the purpose!
I will agree that the double-ended striking bag is better for targeting/ hand-eye coordination.
Just when you think something is foolproof, they come out with a new and improved type of fool.