Why cruisers served as division flagships

What type of ship would normally serve as a naval division flagship?

Usually a cruiser, often a light cruiser depending on the division.

Cruisers were the normal scale of ship for a divisional flagship. A light cruiser would often be sufficient, depending on the formation and commander involved. The choice reflects the need for a platform able to host command staff and communications without consuming a capital ship. It also distinguishes a division-level headquarters from the smaller ships the formation might direct.