Perhaps the reason lies in the difficulty of translating into film terms a process that is essentially internal. A painter can be observed painting, a dancer, dancing. Composers at least get to have triumphant performances of their works.
Writers sit at their typewriters or computers, and then the book comes out.
In and of itself, the process does not have the makings of high drama. Arenas was born into rural poverty and never knew his father. He attended university in Havana and then worked in the national library. His first novel won honorable mention in a competition and was published in Cuba. But Arenas attracted unfavorable attention from the authorities.