The use-case I have in mind is to enable multiple canisters to plug into a common cycle pool (kinf of a cycle dao Completed: ICDevs.org - Bounty #17 - A DAO for Cycles - $10,000 - ht: cycle_dao ) and share a token to access the common resources. This serves as foundation for other public services but the broader vision only works if they are no other ways for the involved canisters to access cycles, otherwise they would be in a position to take advantage of the system.
Plus all of what @Severin mentioned