Nothing wrong with that.
Marriage is an institution and it can be from a lot of reasons. We tend to romantize it and think it's only acceptable to marry out of love but if you separate love and marriage, then love is love and marriage is marriage. Sure, ideally the two would go together and the two parties can live the modern day version of "the happy life", but if you can love without being married, why can't you marry without being in love? Think of it like going into business with someone, as long as both parties agree and thinks it's a good idea, then why not? Like a couple have mentioned above though, both people have got to be ok with it. If you're settling for a friend, make sure he knows that's what you're doing, which is crappy and of course there's probably no way you can do so, but at least try to let him know that you probably aren't as interested in him as he is to you.
I have no problem marrying out of comfort, convenience, whatever you want to call it, and someday I just may do that. I have zero luck in love plus the idea of marriage sounds tedious and too much of a conformity anyways. The idea of me getting hitched with some girl who's gonna give me kids and a nice family is far from being out of the picture. Anyways, There are advantages and disadvantages to every situation, and if you weigh your options and see a good choice, go for it, don't think about what trend society is in or compare it to a "picture perfect life" that way too many people chase their entire lives only to find that it didn't exist for them and they missed out on great opportunities because of it.