Why didn't Microsoft ever come up with a BitLocker Master Key?

The master key is a key that opens several locks, each of which also has its own key. If are asking why there is no one, while I don't have access to Microsoft's internal decision-making processes, there are a few reasons included as follows:

Introducing a master key system could create a single point of failure or compromise for BitLocker-encrypted devices. If such a key fell into the wrong hands, it could potentially unlock a large number of devices, causing a security risk.

Exerting a master key system could raise legal and compliance challenges, especially in fields with strict data protection laws. Companies often need to demonstrate that they cannot access user data without user consent, and a master key could undermine this principle. 

A master key system would require robust key management practices, auditing capabilities, and potentially complex cryptographic protocols. Balancing these technical requirements while maintaining user trust and security can be difficult. 

Instead of a master key, Microsoft and other companies use mechanisms like recovery keys, which allow authorized parties to access encrypted devices under specific circumstances (like a forgotten password). If you think it's insufficient, it is advised to propose your idea about adding a master key to Microsoft official.