All very valid points, and I don't disagree with any of them.
I have personally been in a relationship where we lived together before getting married. I'm not saying it was bad, but I'm not saying it was good either. For me, this isn't just about being traditional or modern. It's a religion thing too. In my last marriage, our faith was not a big part of our reason to get married. We liked sex, and at the time we liked having sex with each other. I wasn't able to see past that at the time. It took us a full year of being married before we both realized how much we didn't like each other as people. We mostly stayed together because of the kid.
With this relationship, we're getting to know each other on a personal level and on a spiritual level, and we're not complicating things with sex. To me, sex before marriage is a product of lust. That may not be the case for many others, but that's just how I see it. Keep in mind, that this was close to eight years ago for me since the last serious relationship started, and I've changed a lot since then. I want sex to come after we know that we love each other and we're fully committed to each other.
Since the whole thing started with giving each other a little more space, the relationship has gotten a lot better. I think I'll know before the wedding date if this is something that is meant to be or not. As of right now, I do and always have thought this relationship was built to last though.