While the physical act is only one small component of a marriage, and we should not put ALL the emphasis on it, I don't think trivializing it is the way to go either. After all, the lifelong pair bonding of a marriage (institutionalized or not) involves the complete trust and forsaking all other for your soulmate. If the physical means nothing, then you open the door to frequent infidelity.

Unless of course its an open marriage and both partners are ok with that, then its no big deal.

Perfection does not exist. The question therefore, is: what level of imperfection are we willing to settle for?