Of course i use a pike, when i see so many cavs around. But unfortunately, there's more cavs in the ennemy team, than pikes in my team, most of the times.
And i believe it must be quite thrilling for cavalry to own this poor pikeman who can't deal with 2 lancers cav, or with one 1h/2h cav constantly bumping and slashing close to him.
But the pike is still fun. Doubt i'll waste heirlooms on it though. For now at least.