How often has there been a WP or a batter swinging at it. Thats all I'm saying. They are always looking at ways to speed the game up. This seems like a logical place to look... IMO.
An IBB shouldn't be codified into the game's rules. That is the way I feel about it. And IBBs do not occur that frequently. A much better way to shave off time would be to institute a between-pitch time limit and a change in the culture that allows hitters to take a billion years to get set up.