I see people who are interested in having a virgin sex partner being mistreated a lot. There are a few different camps of these people.
The first, of course, are those who automatically assume anyone who expresses such a preference is a religious fanatic who will attack the speaker for not conforming to the tenets of their religion. They mistreat those who express a preference for virgin partners as a kind of preemptive attack. Doing unto others before they get the chance to do unto you.
For those who don't automatically assume a religious motivation (or who have already had such a motivation explicitly denied), there are those who still treat it as an attack. They've received so many messages judging them for sexually open behavior, they're certain anyone who expresses such a preference intends to look down on them or attack them for holding a different view.
Next we have the group who treats such an interest as a sign of immaturity. Much like the previous group, they've seen the social messages, but they treat it as a point of pride that they've rejected them. These people view anyone who would express a preference in line with what the mainstream message tells them is "correct" as someone who's too stupid or immature to make their own choices.
After them, we have those who assume anyone interested in a virgin is abusive. They assume that the attraction is all about finding someone vulnerable who will put up with physical and emotional abuse or just plain bad sex without complaint because they don't know any better.
Then we have the people who just plain don't get the appeal, and so attack others because it's human nature to hate what we don't understand. "Why would you want to be virgins on your wedding night? The sex will be lousy because neither of you know what you're doing yet."
For the sake of those genuinely interested in understanding the point of view instead of looking for an excuse to attack, I'm going to try to explain the appeal.
People care about firsts. A baby's first word is important to those who care about that child, even though that's the least articulate that child will ever be, even if all the words that come after will be clearer and convey more meaning. That fist word means something. It's a dividing point where what comes after will be different from everything that has come before. Likewise the first steps are things parents want to catch on film, memories they cherish, even if they're the clumsiest steps that child will ever take.
The first day of school is painful for a lot of parents because that's the first first that the parent can't be there for, can't share with the child.
By the time we're in the process of selecting lovers, partners, spouses, most of those firsts have already passed for both of you. Saving one first to share with a lover is giving them a chance to be there for an important moment, where what comes after won't be the same as what came before.
For those interested in a life partner, someone who you will care about above all others, and who will care about you in the same way, being able to share a first is a means of being a part of their history from that point forward. You may not be able to be there for their other firsts, but wanting to be a part of as many as possible is something a lot of us value, no matter what religion or lack thereof.