In the middle ages (let's just, for the sake of argument, call this anywhere from 600-1600 AD) there were only a couple of types of art--painting and sculpture. There were many crafts including wood working (turning, carving, building), glass (stained, blown and more rarely fused), and textiles.
Today, there are many types of art. But there are a number of people, artists themselves, critics, and "experts" who insist that the only types of art are "fine" arts--painting and sculpture, and even with those avenues, these modern art snobs are quite particular about which mediums count as fine for painting--today oil and acrylic seem to pass inspection, and of course marble, metal and a plethora of other materials for sculpture get the nod as "fine."
Mediums such as watercolor, found object assemblage, paper collage, glass and woodworking are, by art snobs and academia, considered fringe elements in the art world. The irony here is that the middle ages and even the Renaissance were limited in their art. Limited by the availability of materials--paper for example was difficult to manufacture and considered a very costly item so collage would certainly have been seen as an excessive extravagance, not to mention that the availability of mass produced papers just wasn't there. Paintings were primarily done with egg tempera and this was true until the mid 1400s when the Van Eycks and a few others began dabbling in oil painting--a previously unknown medium--in fact, many of the worlds' most cherished "fine" artworks are done in tempera paint!!--a fact which art snobs seem too easily to overlook as they consider modern tempera paint and watercolor to be "less than fine."
Not only were materials far more scarce or nonexistent, the fact is that life was HARD and survival the primary focus. Flat panels of glass for stained glass works were not easily available and only a few "houses" of glass had recipes for making it--it was a difficult medium to create and those who worked with it were more often than not, also the ones who MADE the glass art. Modern manufacturing and technology has eliminated this portion of the "craft" of glass allowing the artisans who work in blown, stained and fused glass to focus more on the artistic methods and techniques of creating artworks.
Textiles were for wearing or keeping warm and occasionally, decoration. Gathering, carding, spinning, dying, weaving...all were time consuming and time in an era of dire survival, was a luxury most people did not have. Still, textiles that are "high" art do exist. One must wonder when textiles dropped off the "fine" art checklist to the mere level of craft. Does it not take as much skill, technique and artistry (albeit, different skills, techniques and artistry) to create an intricately stitched piece of black work as it does to chisel out a piece of marble? Yet textile work such as quilting (some absolutely stunning quilts are in existence and even those that aren't stunning at least require respect for the sheer amount of skill, effort and artistry to piece and quilt), embroidery, knitting are relegated to the area of "craft."
What I'm saying here is that the art world--whether that be Rome, Paris, New York or whichever location will replace New York as the center of the art world, dictates a narrow view and walks a fine line between what they call art and what they consider craft. I would posit that the painter uses as much craft--knowing what brush to choose and how to wield it, which canvas to pick and how to stretch and prepare it--as they do art to create a piece of work. The same is true of the wood turner, the glass artist, the collage artist, the found object assemblagist, the jeweler. The artist is both artist and crafter.