I have been playing weddings for around 20 years within a 100-mile radius of my corner of the American Midwest. These days, and in these parts, wedding preludes offer many people their first chance to hear "classical music" played for them in a quiet place where everyone is listening to living and breathing human beings play it. When an ensemble (I can speak for a string quartet, which is my wedding ensemble of choice) tailors its tempo and mood in response to the tempo and mood of the wedding decor and the wedding party, and adjusts the timings (not to mention choice) of selections to the people getting married and their families, it makes the experience especially moving and memorable for everyone involved.
The quality of the group really does matter. Musicians who consider playing for weddings their performances miss the mark, in my opinion. Musicians who consider playing for weddings "just a gig" also miss the mark. Playing a wedding is about the people getting married, and about their families and their friends. For the bride and groom, this is the first most important day of their life together.
Wedding musicians are indeed humble servants. They are there to make everything sound as beautiful as it looks, allow everything to move properly, and to help people allow their feelings to come to the surface. This is what professional musicians do: they enhance the experience without dominating it.
Ensembles made of professionals do not come cheap, but the current internet-based way of finding ensembles for weddings cheapens musicians. It treats music as a commodity that can be bargained for, much the same way you would take a bid from a building contractor, compare it to another contractor, and hire the one that offers a lower price.
Internet shopping always involves comparing prices and opting for the lowest one, but most internet shopping transactions involve things, and music is not a thing. One organization dealing in the music-for-hire trade charges musicians a modest listing fee, and buys premium space (for its organization) so that its listings come up at the top of regional searches for musicians, thus demoting the ensembles' own internet listing to a place further down on any search engine's listings. Some organizations take a "finder's fee" from clients that is a percentage of the fee that the ensemble charges. Some encourage musicians to bid against one another for jobs, which means that in order to get a particular job, a musician is compelled to lower his or her usual (and often reasonable and modest) fee and/or travel expenses.
Musicians are encouraged to "sell themselves." Internet shoppers are encouraged to respond to musicians' "blurbs" the way they are encouraged to choose one piece of electronic equipment over another. I think that it is safer, for everyone involved, to hire musicians the old fashioned way: by personal recommendation.
People talk about "classical music" (as if it is an entity in itself) being in trouble. I would say that pitting one musician against another in order to get work, and making it possible for "buyers" who don't really know the difference between great and adequate (from what they can learn from the internets) to bargain for lower fees from musicians, is one way to eat away at the livelihoods of professional classical musicians.
Would you pick a doctor or a dentist based on the one who offers the lower fee?