Why was there never an Inception 2?

I'm curious, why do you think there was never a sequel to the film "Inception"? The original film was a huge success, both critically and commercially, and left a lot of room for exploration in the dream-within-a-dream concept. Could it be that the director, Christopher Nolan, wanted to leave the story open-ended and allow audiences to interpret the ending for themselves? Or was it perhaps a difficult film to follow up on, given the complexity of the plot and the mind-bending visuals? What are your thoughts on this matter?