You have a good point.
If I may, let me throw this in: There are many, many people who have an objection, primarily for religious reasons, to the term “marriage” being applied to same sex couples, but who have no objection WHATSOEVER to some sort of process or system of of contractual civil unions for same-sex couples. As a civil matter, this is what marriage comes to - a contractual union.
Might I counter though that civil unions, as of recently, are not entitled to the same rights as actual “church-marriage.”