What's the purpose of a bridal party?

Other than having pictures look pretty and having a bridal shower, why do I need bridesmaids and groomsmen? What is their purpose? Why do I need x number of women standing on my side and x number of men standing on the groom's side? Can't I just save all my friends the hle and not have a wedding party? I'd much rather a small ceremony with just me and my fiance, and have everyone we love in the audience. I'll save them time and money if I just invite them to the wedding. I also don't want a shower or an engagement party; just a small ceremony with a fun reception. What do you think?