Let's not forget they gave almost every enemy some form of teleport that doesn't trigger aoo's.
What's the point of engaging a minotaur or hook horror in melee if they're all going to jump straight to Gale or wherever they want without drawing an aoo from your fighter?
That combined with the AI that actively avoids targeting high AC targets makes for really dumb combat.
And they actually changed the system to work this way from the default 5e logic where melee and zone of control matter. So they must think this is somehow better. I'm not convinced this is the best developer to be making tactical combat even though mostly everything else is top notch.
This is probably why they changed mirror image to grant +9 AC instead of giving you 3 mirror images (and also made mage armor more powerful). In testing, they found that enemies, with the teleport abilities + AI + various auto-damaging attacks, were always going for and murdering the squishy mages in the back. So Larian decided to change spells so that mages' AC would be increased, preventing the AI from targeting them.
That's the only reason I can think of for this change to mirror image, besides just not wanting to animate it..
