Heated shot is probably the most useless and situational tech besides nomads.
Building tower on water maps is never a good idea because prioritizing tower over water units will lead to your opponent having more navy causing them to win water. you could play very defensively but they can just go imperial age and build cannon galleons.
I purpose making heated shot effect archers and also give +1 or 2 bonus damage against buildings excluding stone fortifications. they could also deal bonus damage vs siege though that would ruin an intended counter.