In Thich Nhat Hanh's "Freedom Wherever We Go" (i.e. a revised pratimoksha) the precept against male masturbation is moved from "sanghavashesha" to the "payantika" rules, same level as it exists in the bhikshuni rules. So it is a minor offence for both, while in traditional pratimokshas it is minor only for nuns. On the other hand, touching or letting be touched by another person with both parties having sexual intentions is a defeat for nuns and community restoration for monks. There's hardly any way around the rules to justify the acceptance of sexual activities between monastics.
On the other hand, that's just the theory. There are also social factors to be considered, as mentioned already. In fact, the Vinaya itself was meant to harmonise the monastic community with the prevailing social norms. If the lay community is happy to support a family temple - as in Japan - it can also preserve and carry on the Dharma. There are family lineages in Tibet and they are also doing quite well. I'm not saying that the rules should be thrown out the window, but flexibility and diversity of the Buddhist clergy is a good thing. I believe that it is in agreement with the Mahayana idea to allow a greater variety of Dharma professionals than what is in the Vinaya.
"While teachers of the middle way, mind only, transcendent wisdom, mantra, and other schools may have their own assertions, the fulfillment of those intentions is the same. There is not a single thing that is not contained within mind."
(Gampopa to Düsum Khyenpa, in "The First Karmapa", KTD Pub, p254)
“If you recognize the world of appearance and existence as the mind, realize the mind itself as empty, and have no grasping at the superiority of your realizations — this is the ultimate view."
(Chegom Dzongpa, in "The Book of Kadam", Wisdom Pub, p609)