How is the commercial aspect of art different today than during the Renaissance?

Most arts throughout the Renaissance era was done by the commission. A patron proceeded to the artist and told them what it was that they needed, and all aspects of the business were hashed out ahead of any original creative work being done: pay, time to complete the work, what medium would be used, and the material of the work. A Renaissance-era artist had the satisfaction of knowing ahead of time all he would need to complete such work, to the detriment of very little artistic license. More contemporary artists, mostly working for their own benefit and with their own creative drive powering their work, must work absent this same "patronage", and create what is popular or likely to sell and assign a value to their own work based on commanding market value and demand.