Yes, it matters.
I think 75% of relationships die down from being madly in love to just loving each other, and that most of those will survive. At least half. In those cases, the people involved know that it has died down to just loving each other, but loving each other is still big and so they are okay provided that no-one falls in love with someone else.
In your case, if your feelings lessen over the years, you'll be left with friendship.
Is your DP in love with you?
You could be describing me and OHs relationship with your first paragraph, but we did have a crazy intense bit, and we are in love. Both of us. And if I wasn't in love with him but did love him, I'd let him go. I broke up with my ex-boyfriend after 5 years because he both loves and was in love with me, but I only loved him, and he deserved better. He didn't see it at the time, but he does now, and he is happier for it. He deserves the happiness he has now.
I don't think only a few people are ever in love. And of course you hear a lot about relationships that fall apart, because generally those are the people who reach out to other people, because they need help/hand holding/someone to talk too. That's true on here, in real life, on TV...people who don't have issues don't talk about them.
Have you been in love? If you have, I can't really understand how you could think that just loving him was enough. I really don't think it is.
That said, if it's as good as you say, I don't think you should just give up on it either. You might fall in love with him over time, or you might have to make an active effort to try and fall in love with him and see if it happens, or you might never be in love with him at all. But I don't think you should marry him while you aren't in love with him, because you will fall in love with someone, and it'll cause ten times the devastation if you are married or have children.
I'm sure other people's opinions will differ because this is one of those things you have to do for yourself, but I'd hold off on marrying him for a while. You don't need to tell him, just cool it a bit. Because comparing the two situations, I couldn't have stayed with my ex, who I really loved more than anything and had planned a whole future with...we'd even saved a deposit and talked about venues...having met and fallen in love with my OH.