Well they have basic AI, actually. Zombies have extreme tracking range, skeletons shoot faster the closer you get, and the most Creepers have is they avoid cats. Otherwise, they follow the same rules.
What I'm saying is, say you don't think Creepers should use the standard AI intelligence/be more visible and less able to maneuver. Just trying to clarify that the AI is actually still pretty lazy. He overhauled it so they aren't humping walls or similarly anymore, but besides attributes they add, the AI is still pretty crappy. (One thing I can note is the old AI took the Void into account, having mobs avoid walking into it. The new AI seems to count air blocks when calculating drops, and since the void doesn't have air blocks in it, it is essentially treated as a solid floor. Mobs will walk right into it if they wish to drop down for some reason.)