Within the magical community, it is much more than just equating it to mixed race couples in the muggle world. A muggle-magic family would be extremely hard to function. Remember that muggles can't see many things that wizards can. For example, muggles can't see the Leaky Cauldron. Would that change once they marry a witch or wizard or have a magical child? If a muggle woman marries a wizard, would he have to lead her by the hand into the Leaky Cauldron or would she now be able to see it because she would then be conscious of the wizarding community.