The concept of "bundles" were introduced in D7 by Field API, before there was a formalized notion of entities and an Entity API.
Modules providing fieldable entity types needed to notify Field API when bundles were created, renamed, deleted, so that Field API could perform the corresponding housekeeping. Hence field_attach_[create|rename|delete]_bundle() funcs, and associated hook_field_attach_[create|rename|delete]_bundle() hooks.
Managing bundles, however, is not the job of Field API, and should be moved over to the Entity system. The current code in the API functions (besides invoking the hooks) should be kept as Field API's implementations of hook_entity_[create|rename|delete]_bundle().
PASSED: [[SimpleTest]]: [MySQL] 54,027 pass(es). View
FAILED: [[SimpleTest]]: [MySQL] 53,909 pass(es), 1 fail(s), and 1 exception(s). View
FAILED: [[SimpleTest]]: [MySQL] 53,873 pass(es), 3 fail(s), and 2 exception(s). View