Same reason they should own access lines: everyone needs rackspace/access, it should be treated like a public service to avoid rent seeing. Having a data center in every city where all of the local lines terminate into could open the doors to a lot of interesting use cases, really help with local resiliency/decentralization efforts, and provide a great alternative to cloud providers that doesn't break the bank.

should the government own all types of "public services"? e.g. search index, video serving infra, etc?

Public ownership of public services hmm?

Smells like socialism. Around here we privatize the profits and only socialize the costs. Like the impending bailout of the most politically connected AI companies.