The author mentions the best-seller lists and the Book-of-the-Month Club primarily to emphasize Raintree County's:

This choice suggests that Raintree County has a small audience, which contradicts the notion of it being featured on best-seller lists and the Book-of-the-Month Club. These platforms typically promote works that have broad appeal, thus indicating a substantial readership rather than a limited one.

While Raintree County may possess enduring qualities that attract readers over time, the mention of best-seller lists and the Book-of-the-Month Club focuses more on its immediate commercial success rather than its long-term popularity. Enduring appeal would imply a lasting interest rather than current sales figures.

Artistic aspirations pertain to the creative intentions of the author or the literary quality of the work. While Raintree County may have artistic merit, the author's focus on commercial indicators like best-seller status suggests that financial success is the primary emphasis rather than artistic goals.