It's the only way to keep units in nice tight ordered ranks that doesn't involve possibly crazy broken EDU changes, and works well enough on the offense too.
*ahem*

Allow me to bloviate on the benefits of short_pike.

BEFORE they get short_pike trait:

They march with the tops of their spears magically dragging beneath the ground and their butt spikes in the air.
AFTER they get short_pike trait:

They march with spears held level and pointed forward.

BEFORE:

They break formation and charge like unorganized rabble.
AFTER:

They stay in a tight, orderly formation and slam into the enemy as one - an invincible, unstoppable phalanx.

BEFORE:

They fight like barbarians, individuals fighting for personal glory with no resemblance of a formation.
AFTER:

They fight like, well, a phalanx! A single, implacable body pushing the enemy backwards with great force until they finally break and run.

As we can see, hoplitai behave far more accurately and realistically with short_pike than without it. If anything, they ar more bugged without it, as I have just shown.