It worked in 1.2, but I don't think it is working properly in 1.3. I tried assigning it to Poeni. What I found was that they stayed in the basic phalanx formation even when it was toggled off in game. They did have the shorter spears (more like a true early hoplite length, which is what I was going for), so it is doing something, but it doesn't seem to be the same as before, where they shouldered their pikes.

As to effect in 1.3, while phalanx was toggled on, I found that attacking sword units completely penetrated the "short_pike" spear wall. They went right through it and engaged in sword melee with the phalangites. Very few of the spearmen were able to continue using their pikes. I don't remember it being quite like this in 1.2, but it has been many months since I experimented with it there.

It might have been forgotten when the 1.3 patch was ported.