This is a rather reductive view of quantum cryptography. The two most common applications of it I hear about is the development of encryption algorithms resistant to being broken on quantum computers (the way, say, Shur’s algorithm is known to break RSA) and techniques like quantum key distribution. Both of these are real problems that don’t become meaningless just because one-time pads exist - you need to somehow securely distribute the keys for one-time-pad encryption. That’s why one-time pads aren’t used everywhere (“it would cut the whole internet bandwidth in half overnight” would not have been a sufficient reason - that’d be a tiny price to pay for unbreakable encryption, if it actually worked).
This is a rather reductive view of quantum cryptography. The two most common applications of it I hear about is the development of encryption algorithms resistant to being broken on quantum computers (the way, say, Shur’s algorithm is known to break RSA) and techniques like quantum key distribution. Both of these are real problems that don’t become meaningless just because one-time pads exist - you need to somehow securely distribute the keys for one-time-pad encryption. That’s why one-time pads aren’t used everywhere (“it would cut the whole internet bandwidth in half overnight” would not have been a sufficient reason - that’d be a tiny price to pay for unbreakable encryption, if it actually worked).