There is no joy except in marriage.

The Rosh there wonders exactly about this: What is a chuppah, if in the place where the blessing of marriage is said, i.e. the beginning of marriage, and to call it a chuppah, it is not possible, sometimes when it is said on a city street when the people are in large numbers, but in the place where the bride and groom are mainly sitting, i.e. a chuppah, and not in a place that is made randomly, and it is customary in Ashkenazim to make a canopy for the seat of the bride and groom, and it is called a chuppah. Nowadays, they don't do that, and probably because it involves expenses (renting the hall over and over again). By the way, the Rambam and Shulchan Arius brought the law regarding the sukkah, but I did not see that they brought the law regarding holding a celebration instead of a chuppah.