I want to clarify that when I said people change, I was referring to the finished product as a result of the way they were enculturated and raised. people are different today because they have been raised to be different... it's certainly not an ontological difference by any means, though.
reconstruction attempts to restore a previous cultural system that would allow for the 14 yr. old girl to old man scenario are doomed to failure; even if you raise the 14 year old girl into that type of culture and raise her correctly, the middle aged man was certainly still not raised correctly to be able to honor the way such a thing ought to have been done in traditional society. this is just one area where is is not possible to healthily turn back the clock fully... this doesn't mean we ought to condemn what used to be done, but we ought to say it cannot and should not be done nowadays. that might sound similar to a lot of modernist arguments; but the difference is on this issue those arguments actually apply whereas on other issues they do not apply, because the way people develop sexually is very important to what mode of marriage they are able to healthily live out.
there are a lot of people in modern society who have been so severely messed up that they may not even be fit for any type of marriage at all. the way we were raised, we are only fit for a limited scope of age difference until we're around 18; once that age is reached, however, age difference even to some extreme levels is perfectly possible (and of course, that age doesn't stand as the end-all-be-all for every person, it is different based upon the individual)... but the way we are raised leaves us predisposed to need to marry within our own age group if we are raised young... and I'm sorry but you pretty much cannot find any way in modern society to raise your children to effectively be of the same mental capacity for marriage as they were in medieval or ancient times. the whole society would have to change radically for that.
arranged marriages are fine; forced marriages are not. there must be the free consent of the will for a marriage to be effective, either by sacrament or natural law.
in an arranged marriage, there must be an opt-out possibility; though some degree of pressure is allowed (there's still parental pressure exerted even when marriage is decided according to modern courtship/dating rituals), ie the rejection of an arranged marriage might be taken as an insult to your parents, your family, or the family of the one you were arranged to marry and all the consequences of that insult would have to be dealt with.