É por causa das políticas da Federação dos Planetas Unidos. O Manual Técnico da TNG tem isto a dizer sobre o assunto (Para aqueles que seguem em casa: Seção 11.6, 'Políticas Táticas').
Starfleet draws proudly on the traditions of the navies of many worlds, most notably those of Earth. We honor our distinguised forebears in many ceremonial aspects of our service, yet there is a fundamental difference between Starfleet and those ancient military organizations. Those sailors of old saw themselves as warriors. It is undeniable true that prepairedness of battle is an important part of our mission, but we of Starfleet see ourselves foremost as explorers and diplomats. This may seem a tenuous distinction, yet it has a dramatic influence on the way we deal with potential conflicts. When the soldiers of old pursued peace, the very nature of their organizations emphasized the option of using force when conflicts became difficult. That option had an inexorable way of becoming a self-fulfilling prophecy.
Today, peace is no easier than it was in ages past. Conflicts are real, and tensions can escalate at a moment's notice between adversaries who command awesome de- structive forces. Yet we have finally learned a bitter lesson from our past: When we regard force as a primary option, that option will be exercised. Starfleet's charter, framed some two centuries ago after the brutal Romulan Wars, is based on a solemn commitment that force is not to be regarded as an option in interstellar relations unless all other options have been exhausted
(negrito meu, itálico é textual)
Mais abaixo na página diz:
A starship is regarded as an instrument of policy for the United Federation of Planets and its member nations. As such, its officers and crew are expected to exhaust every option before resorting to the use of force in conflict resolution. More important, Federation policy requires constant vigilance to anticipate potential conflicts and to take steps to avert them long before the escalate into armed conflict.
Mais tarde (não vou digitar a citação completa porque meus dedos doem por digitar tudo isso!), eles afirmam que "há situações em que uma nave e sua tripulação podem ser consideradas dispensáveis". Assim, a Federação atribui um alto preço à paz / perda imediata de vidas. Logicamente falando, ir à guerra causa mais perda de vidas a longo prazo, por isso, se você considerar o aforismo "A vida dos muitos subalternos, a vida de poucos", então também é uma escolha bastante lógica.
Portanto, a tripulação está apenas aderindo à política destinada a preservar a paz (e não tenho dúvidas de que Picard teria valorizado e apreciado muito essas políticas).