In some ways starfleet philosophy is its own religion. A mix of Vulcan stoicism tempering jet-age manifest destiny with a side helping of gunboat diplomacy. A belief that individuals united under common cause and ethics can and therefore have a moral imperitve to improve not only their own localities but to find new ones and improve them as well. The UFP is an organization that thrives by expansion, much like borg. It needs new converts. When it is static, the corruption kicks in.