Ummamumma, that isn't the case everywhere. Under Canadian law you can only get an annulment on grounds of non-consummation for inability (including "invincible repugnance to the physical act of consummation, resulting in a paralysis of the will" as well as physical inability), not wilful refusal. If someone refuses without reason, then the only way out is a divorce, even if you're the gagging-for-it party. It isn't an essential component of marriage there, unless there is a complete physical inability to perform.
This is what tends to get to me about discussions about marriage. People say, "marriage is X!" and then cite English & Welsh law as evidence of that statement. Which is fine, except that they're extrapolating that to mean, marriage can only be X. Marriage can encompass an awful lot of models. And even in this country, your belief that non-consummation can always be relied upon if the non-refusing party wants an annulment is misplaced: there are cases where older people, who agreed before marriage that they won't have sex, have then been unable to get an annulment where one of them changed their minds afterwards. And an unconsummated marriage is not void - only voidable, if the non-refusing party wants out on that basis. It's not as simple as, "if sex is not involved, it isn't a real marriage." It's completely valid if both parties are happy with that. No outsider can claim a marriage is not valid just because no sexual element is involved, because only the party wanting sex, but not getting it, has legal standing to void it. Nobody else. Unless and until they do, a sexless marriage is as valid as any other.
Marriage isn't something set in stone. It's human created. We can and do change it. That's why I am happily esconced, as a feminist, in an institution that used to essentially make slaves of women. But I don't see why "this institution suits me" translates into "it suits me, so if you were reasonable, it would suit you". I don't care if I understand other people's reasons. It's a big deal, and therefore a model that would suit a big chunk of the population, currently unwilling to enter into the existing one, should at least not be dismissed out of hand.