when it is obvious that the pitcher is intentionally throw balls to walk the batter, why cant he just say "walk" instead of throwing 4 balls?
In many levels, this is allowed, but not in pro ball. As crazy as it may seems, occasionally things go wrong on an intentional walk. The basic problem is that this is not something that is practiced, and every once and a while, a stray pitch may get by the catcher, or worse yet, be hit by the batter. The former happens a couple times a year, the later happened about 5 years ago*, with the batter driving in the winning run. Yes, I'd agree that greater than 99% of intentional walks go off without a hitch, but whenever the situation occurs that an intentional walk is warranted, a mistake is always costly.
*Yes, Giles, it was the Orioles that gave up a hit on an intentional walk.