I agree fully, and I often bring that up in discussions like this one. If things aren't done carefully, you can end up with just a single way to play this game... or even worse, no way. Swimming zombies solves the problem of people avoiding everything by simply swimming into the middle of a lake. That problem to solve was just as bad as the digging down three blocks problem. Other ideas were proposed to solve this, but they were not well received.
In general, all AI in games needs to be beatable. Finding the methods to beat AI should require effort and skill. This goes all the way back to the first AI in games... PacMan. By understanding the 4 different AI behaviors of the ghosts, someone can eventually beat it on a pro level. Figuring out the AI and beating it is not exploiting it, it's understanding it, adapting to it, and skillfully defeating it.