Why do so many animals on our world have pointed ears?

It's simply a useful shape for funnelling sounds into the ear. Ears are also used for signalling mood in many species, so they need to be large and mobile enough to be seen and moved according to how the animal feels. We have deprived many breeds of domestic dog of their ability to communicate properly by breeding them with floppy ears and docking their tails - wolves, their ancestors, use their ears and tails a lot in communication.