One of the sacred and most enjoyable aspects of the rabbinate is being amesader kiddushin, joining two people together in marriage. Yet for many rabbis acting as a mesader kiddushin would seem to be in violation of a rabbinic admonition that "whoever is not expert in matters of divorce and marriage should have nothing to do with them." (Kiddushin 13a) Traditionally the laws of marriage and divorce are not part of the rabbinic curriculum and only those rabbis who have yadin? yadin! semicha are trained in this area[1]. And treading in these waters without training - both in "class" and in the "field" - would be most foolhardy. Make a mistake - even an honest unintentional one - and we are looking at potential adultery and illegitimate children who through no fault of their own may be unable to marry.
In no other area of Jewish law is a mistake so severe and permanent. Not in monetary matters, questions of kashrut, Shabbat or Yom Kippur is a mistaken ruling so devastating. It is best for all involved that we leave such matters to the experts who are few and far between.  
So why do so many rabbis officiate at weddings without specific intensive training? Lest one think that allowing all rabbis to perform weddings is some modern phenomenon, this question bothered the Maharsha, Rav Shlomo Eidels in 16th century Poland. He too wondered why "permission was given to those who knew even a little" to perform marriages. 
He explains that our Sages only required experts with regards to a divorce. Performing a halachic marriage is quite easy; it is divorce law that is most complicated and only there are experts needed. As all who have "even a little" knowledge of these areas know the Maharsha is undoubtedly correct. As the Maharsha notes a close reading of the admonition of the Sages bears this out. With marriage being a pre-condition for divorce our Sages should have said "whoever is not expert in matters of marriage and divorce" should not get involved in them. Why then did they reverse the natural order and put divorce before marriage? The Maharsha explains that our Sages were admonishing those who perform a second marriage to ensure that they are expert enough to ensure the prior divorce was done properly. It is kiddushin after gittin that requires expertise but not kiddushin itself. That our rabbis were most concerned that kiddushin after gittin be in accordance with halacha is the reason that masechet Gittin comes before masechet kiddushin in the order of the Mishna. 
This idea finds expression in the Biblical text itself. Many of the laws of divorce and marriage are derived from the expression "vyatza vhayta, she went out [divorced] and came in [marriage]" with marriage coming on the heels of divorce. In fact the entire presentation of the laws of marriage and divorce are little more than a prelude to the main context of the text; that of the prohibition to remarry one's previously divorced wife if she had married in the interim. The Torah does not approve of spouse shopping and while one can remarry one's divorced wife that is not so if the wife has married in the interim. It is this particular marriage after divorce that the Torah prohibits. 
That it is easier to marry than to divorce reflects the primacy of marriage in Jewish thought. While there are three possible ways to marry there is only one to divorce. And while misspelling one letter of a name of a get may render it invalid[2] there is no set formula for marriage. The Talmud lists many phrases that one can say to effect a marriage well beyond "behold you are betrothed to me according to the laws of Moses and Israel." The fact the one may marry by speech but one needs a document to divorce is most instructive. In fact one can marry in silence. Just giving a little gift in the context of discussing marriage may be enough to declare the couple married. 
While separating a couple is to be left for experts, bringing people together is a role all should be able to fulfill. 
[1] In Europe most questions to the Rav were in the areas of kashrut - ready to eat  koshered meat is a most modern phenomenon - and that is what semicha focused on. There is no - at least in the Orthodox world - set curriculum today for what a  Rabbi must know and standards vary widely to say the least.
[2] While this may seem harsh this should be readily understandable in our exacting and scientific age. Get one number wrong when entering a password, making a phone call or miscalculate an Olympic race by 1/10th of a second and the results are much different than intended.