I asked a museum curator who is quite knowledgeable about Beauford and his works about this and received a detailed reply that I have paraphrased below. According to her:
The first thing to understand is that permanent collection gallery space at any and every museum is limited. Because the goal of museums is to convey as much of the story of art history within its purview (decades, centuries, etc), a certain amount of space has to be allotted to each movement, each period, etc. There may only be the space of one gallery available to show some movements.
Display at Knoxville Museum of Art (2005)
Photo courtesy of Sue Canterbury
Works by the most famous artists are assured of exposure. “Big name” artists such as Jackson Pollack are generally favored over artists such as Beauford (both are abstract expressionist painters from the same time period) because Pollock carries more name recognition and may serve as a bigger draw as far as attendance is concerned.
Whether something is displayed also depends on the strength of the work. Not everything an artist creates is equal – all have their "off" days or experiments. A curator wants the best representations of the artist's work on view to show the artist at his or her peak. The goal is to always raise the bar of quality of the gallery overall.
If a museum owns several works by an artist and they all are reasonably good, one or maybe two will be hung. Assuming the museum doesn't have enough space to indulge in an installation of all the holdings for this artist (which most places don't), it could opt to rotate works every once in awhile to show all of them.
Works on paper cannot be permanently displayed. Watercolors fade with too much exposure and the paper used in prints and drawings can often start to brown prematurely with too much light exposure (depending on acidity content of the paper). I learned about this firsthand when I viewed the watercolor and gouache painting below at the Art Institute of Chicago. It is located in the museum's Prints and Drawings department. The colors of the work are badly faded, so the department keeps it covered and in the dark.
© Discover Paris!
The condition of the work also figures into the decision on whether to display it. Showing a damaged or dirty work would not serve the interests or image of the artist; most people cannot imagine what the work would look like without the damage and the dirt. As an example, viewing a painting with yellowed varnish is like looking at the work through a yellow filter: it extracts the blues from the colors. Thus, blue looks green, green looks yellow, red looks orangish and orange looks yellowish. Fresh yellow looks like dirty harvest gold. White, of course, looks yellowish. Thus, the palette of the painting is completely askew from what the artist intended. This altered color palette can even alter the way in which we read perspective and distance within a painting.
Add to this the fact that most museums are strapped for conservation funds to repair and clean paintings and other works. Things get dirty just by being displayed. Sometimes film deposits caused by the HVAC (heating, ventilation, and air conditioning) system settle on the surfaces, "clouding" the appearance. There are the children who run uncontrolled by their parents and touch things, leaving prints (the oils from which collect dust and dirt and disrupt the continuity of surface appearance), write on them, sneeze on them, or even run into them, causing dishing or tears in a canvas. Museums prioritize the cleaning of the most important works that are already on display (iconic works, works by the most famous artists). Condition and upkeep is an endless, circular process.
Sometimes, a work by an artist may not fit well into the “narrative” or the aesthetic arrangement of the room in which it would be displayed – it clashes with the other works in the room because of its color palette or spirit.
We can’t forget about the “politics” of art – certain works on display could be on loan to the museum from an important donor/foundation that “requires” them to be on view. Otherwise, the donor could withdraw the artwork and possibly decide not to make permanent gifts of the desired pieces to the museum.
Finally, a curator may not like a particular artist's work and thus, decides to put it into storage.
So the fact that Beauford’s work is “off view” at certain institutions may not be an arbitrary decision. For specific answers, it is necessary to contact the individual institutions to find out why they are keeping their Delaneys in storage.