If I were in charge of minting identifiers, I would always just use the http URI schema; the controller/verification stuff could be simply appended right there. With just a modicum of care and planning, the URIs will last as long as the Web itself. http://enwp.org/PURL http://w3id.org
DIDs allow for creating network wide identifiers that can be digitally verified. They work great in conjunction with verifiable credentials. So now you can keep and share records on students using their DID. You can create a unique DID for each student, even a unique id for each record which maps back to the student's DID.
It may not seem like much, but it forms the basis for creating systems where identity can be kept private, even from the individuals administering the system.
> The need for globally unique identifiers that do not require a centralized registration authority is not new. UUIDs (Universally Unique Identifiers, also called GUIDs, Globally Unique Identifiers) were developed for this purpose in the 1980s and standardized first by the Open Software Foundation and then by IETF RFC 4122.
> As a rule, however, UUIDs are not globally resolvable and URNs – if resolvable – require a centralized registration authority. In addition, neither UUIDs or URNs inherently address a third characteristic – the ability to cryptographically verify ownership of the identifier.
TLDR: We've used UUIDs for a while now, they're cool and all but don't work in a distributed network as they assume location-addressing to one central, verifying server. Instead, DIDs work via content-addressing, making them more ideal in distributed networks as they're easier to verify.
But as you say, if you're implementing something that doesn't require global identifiers in a decentralized/distributed context, don't use DIDs :)