Pirate Fan,
My view of this situation is a bit different than yours.
If the pitcher wants strike calls he doesn't have to hit his spots, he has to hit mine.
As the umpire, I set the zone. I understand what you mean by the "borderline" pitch but I don't use it to reward the pitcher with good control. Nor do I use it to penalize the pitcher with poor control. If it's a strike for one, it's a strike for the other. It's just that the pitcher with good control will get the strike call more often because he'll throw it there more often.
I've stated before on this site that I tend to set my zone appropriate to the age group. 13 year olds aren't going to be held to the same zone as Varsity pitchers. I know that some umps don't agree with that philosophy but that's ok.
I can live with it.
As far as pitchers who "flip out"....that's another matter. I guess that could mean a number of things. If you mean he takes a couple of steps down from the mound with that nasty look on his face because he wanted the pitch that I just called a ball then I 'll talk to the catcher first. You know; turn my back to the pitcher, dust the plate and remind the catcher that it's his job to keep his pitcher up on the mound. Usually the catcher understands and goes to talk to his pitcher. If he doesn't, I may add that if his pitcher continues to act that way he probably won't be pitching much longer.
At that point the catcher definitely understands and goes to talk to the pitcher. This usually takes care of any "flipping out" before it happens. If the pitcher still doesn't get the message and comes down from the mound or acts up again, then he can spend the rest of the game counting pitches for his reliever.