Signatures allegedly lower the fraud rate, or at least assist in proving fraud if a card is stolen.

Some banks now offer the option to bypass signature capture at the tradeoff of a slightly higher merchant rate. Many quick-serve restaurants (Chipotle comes to mind) will take the hit in return for processing customers faster. Time is money.

Given how badly I sign the UPS pad when picking up a delivery, I can't see these signatures as being usable.