Why did Britain think the Waitangi Treaty was a good idea?

Signed in 1840, the Treaty of Waitangi is an agreement between the British Crown and Maori. It established British law in New Zealand, while at the same time guaranteeing Maori authority over their land and culture. The Treaty is considered New Zealand's founding document, and marks the beginning of permanent European settlement. With the signing of the Treaty, British Governor William Hobson declared British sovereignty over New Zealand, and the colony of New Zealand was formally proclaimed on 3 May 1840. This resulted in an increase in the number of British migrants to New Zealand and, quite simply, expansion of the British Empire.