For the most part, I rather like the direction that this change is heading. However, I have some concerns about possible game balance.
First, by having the jungle creatures target the nearest opponent, we are removing the ability for mid lane to "leash" the monster. This could prove to be very problematic for off-junglers who really need the aid and damage from mid and top during those two to three seconds that the golem is leashed.
Second, I'm worried that these changes may also take some junglers back out of the game. Specifically, Sejuani. Most of what she has going for her is that ability to deal damage to all of the creeps in the jungle and her single target jungling ability is not so strong. Secondly, successful build for sejuani rarely incorporate much more than beefiness. What is going to be done to keep junglers that build tanky and deal AOE (Malphite, Sejuani, Maokai, Nautilus) in the game?