Honestly I could see arguments going both ways. Pairing prevents unauthorized access, but at the same time, pairing means you need to be able to pair without having a paired device on-hand.

For a passive read-only device (like most satellite/cable receivers 20 years ago), it was probably more important to allow customers to easily replace their lost remotes than it was to prevent pranksters (who could often be dissuaded by more physical means).

Game console manufacturers figured this out ages ago. Press button on the console, press button on the controller, they're now paired