You are correct, but lets not pretend the 7d zombies are no longer "straight line", they still just move towards you like homing missiles, but just thanks to ability to build vertically there is a challenge in making the routing and pathfinding work three dimensionally... The fact this game is voxel/sandbox is a curse and blessing. Curse for AI programmer, blessing for us

... and it is getting there. Currently the bigger issue are the animations of them getting up to you. For example the funny jump they do... just let's animate them climbing blocks, the jump is awkward, right? Mocap of actor just making his way up a 1x1m block. Let's have animations of zombies interacting with world blocks, some different shapes too... that will make them fit in. Some turning animations, more attacks, let them grab players... the combat is so stiff thanks to the poor animations. I must admit I never was a fan of the mocap anims introduced in A12, to this day there are certain animations where I just dont see a zombie, but a mocap actor doing a stunt, it feels so off and over-acted, there is no proper art direction to it. But I hopefully consider all of that early iteration and hope that all of that too will get proper love like the rest of the game.
I consider the current zombies (and combat, thanks to the zombies) to be the biggest technological debt of this game. Rest of the game is getting to a acceptable forms and it is all shaping up nicely, but the zombies are not yet in that comparable state (especially animations, less so models and AI - that all has been worked on a some amount and the models presented are that work), but I would equate current zombies to the quality of early minibike and we all know and remember what a "fun" ride that was

thank god for the current state of vehicles, even though not perfect it is already acceptable quality gameplay.