Why do gay people think it's that important to get married

First of all I think it's great gay people have equal rights and we have come this far in acceptance

I just wonder

Why is it so important for gay people to participate in the ancient tradition of marriage ?

I always saw gay people in a modern way, breaking with the traditional narrow minded past.

Why isnt an official partner status not enough ?

So why is this marriage thing that important ?

Is it to get some confimation being gay is accepted ?

Is anybody still doubting the latter ?