What if I want to have my wedding in a garden, at a hotel, or on a beach?

Before we can answer this question, an explanation is in order about why the location of your wedding matters so much.
The Sacrament of Marriage is a sacred event for both the couple and for the Church as a whole. The Sacrament is a sign not only of the love of the couple for each other, but of the love of God for the couple and the love of God for his people.
With rare exceptions, all of the sacred events in the life of Catholic people (Mass, baptisms, funerals, weddings, ordinations, confessions, confirmations, etc.) are celebrated in a Church — at the sacred place that is the center of our life as a faith community, the place where Jesus Himself is really present in the Eucharist in the tabernacle. The church is also the place where past and future generations (our ancestors and descendants) have and will worship — so when we gather there we act in solidarity with all of God’s people past, present and future.
That is also why weddings are supposed to be celebrated at the home parish of either the bride or groom (by custom, it is usually the bride’s parish) — so that your own part of the universal Christian community can come (at least symbolically) to be witness to and supporters of your Sacrament, in their own special holy place.
Essentially, location has meaning, just as the words of the marriage vows have meaning. Sacred events belong in sacred places, and secular events belong in secular locations. The requirement of Canon Law reminds us of the sacred nature of marriage, the special participation of God and His Church, and the place of every marriage in the life of the Church. A catering hall, a park, the beach, or city hall, are not sacred places, however nice they may be — they are certainly not places where the Catholic people ordinarily come together to worship God in the presence of Jesus and each other.
So, by all means have a wonderful wedding reception at an appropriate secular location. But the right place for your sacred exchange of wedding vows is a sacred place — in a church.