11 Reasons You're Wrong About Solo: A Star Wars Story
2. Darth Maul's Reveal Makes Plenty Of Sense
While Darth Maul's inclusion in Solo did seem a tad self-indulgent, it did serve a purpose in further reiterating the thematics of Solo's story.
Speaking to Io9, screenwriters Lawrence and Jon Kasdan spoke of how Maul's inclusion further intimated the scale of Star Wars' criminal underworld, and how that, no matter how far you rise up the chain, "evil or good, you’re not in control of your destiny... Everybody serves some greater God or is mastered by something.” Maul, serving as a neat callback to one of The Phantom Menace's two redeeming features, encapsulates that in the extreme.
Maul's inclusion also sets up either one of a Solo sequel or an Obi-Wan spin-off. Given the financial reaction to Solo it's likely that the latter is the more probable choice, and though Maul's journey ended in lethal fashion in Star Wars: Rebels, there are still more stories to be told with the character - why else would they include him?