Why do they have to throw 4 pitches for a intentianal walk........?

Question

why cant the catcher just signal to the ump for the walk???

Answer 1

Because they have to make it all "official"

Answer 2

In case there is a wild pitch or something like that.

Answer 3

It takes four non-strike pitches to make a walk. The rules do not define special circumstances based upon the defense's intent.

I'd like to see batters, obviously facing the IBB, swing at two of them, wear down the pitcher that little bit more (even though IBB pitches are easy lobs).