Equity method goodwill or gain on bargain purchase

Hi Mike,
IAS 28 Para 23(b) states that gain shall be recognised in profit or loss to the extent of excess share of net fair value of identifiable assets, liabilities and contingent liabilities over cost of investment in associate. Could you please explain the rationale behind this? Why the gain is to be recognised in profit or loss though the consolidation is not required?
Thank you.