certainly well written, and you are right nobodies' right to vote is being abridged here. however the constitution of the United states affords us many rights one of which is the right to due process and equal protection(14th amendment).
wikipedia> nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.
Equal protection has been used repeatedly in the courts as a way to show the clear and un-bar-able "right to contract" protecting companies and individuals right to make agreements and have them be enforced and recognized by the state.
looking at the nuts and bolts way that the state approaches "marriage" as a form of contract similar to a corporate merger: tax differences, medical rules regulations, inheritance, general ownership of property. Baring an entire group of people from this right to contract is very clearly an abridgment of those rights and the protections brought by that form of contract.
This is why this issue has made such clearer and easy headway in the courts where the rulings are based more clearly on the law it self and the precedent of situation.
your argument though well written is more of a red herring fallacy trying to distract from a very real issue that you paint as more serious to trivialize what is really an important issue in our system of governance.
The women's suffrage movement was more than just the right to vote it spoke to how we define equality in this country. And this modern incarnation of that same discussion (which has taken many shapes over the years color, disability, language) is similarly important though it may feel distant to YOU because it impacts a sub-segment of the population not as large as say 50%.