A possible negative scenario: They grant themselves these rights and then get spun off / acquired by someone with malicious intent. The rights never expire... Can you guarantee that your company will respect the rights of users a decade from now? A century?
Also, you now can't ever sell exclusive rights[1], because there's a perpetual sub-licence capable party floating about out there.
[1] IANAL, but I think that's how it would work; for any licenceable aspect which you wish to grant exclusively, they can grant the same to one or more others, making it non-exclusive.