Well, it was for an expansion, so it was definitely an afterthought. The point is, you already have units with path-following, why code something new when you already have what you need? I believe this sort of thinking is important, especially for indie devs. Game AI is rooted in this philosophy - "It doesn't have to be smart, the player just needs to believe it's smart." Game development in general is about providing the best experience possible with limited resources so looking for ways to leverage your resources is important.