Why command cruisers were usually ordinary cruisers with flag facilities

Were there command-cruiser classes analogous to destroyer leaders?

Not usually; the role was filled by cruisers equipped with flag facilities, and larger cruisers could accommodate those command spaces more easily.

The answer defines a command cruiser by its flag accommodation, radios, and information systems rather than by a unique hull type. In the Second World War period, many cruisers could embark a flag staff, while some received the necessary facilities from the outset. Larger ships such as Edinburgh and Belfast had more room to absorb those spaces. The result was a functional command ship without a separate command-cruiser class.