Why is the issue of marriage an important one to the gay rights movement?

What will be an ideal response?

The possibility to marry is important not only as a right in itself but also because it affects other rights and public policies. Even the simple act of filing a joint income tax return is not available unless people are legally married. Opportunities to acquire Social Security benefits from a spouse also depend upon being recognized as married. The list of policy consequences of marriage is extensive, the point being that marital status has a range of direct and indirect benefits for citizens which were being denied for gay and lesbian couples.