We don't "need" anything, but it would make for a far more interesting story than a Han Solo prequel.
The actual Star Wars spin-off film I want is never going to happen anyway. I would love to ee a completely different film within the Star Wars universe, a serious drama or something set on Coruscant or some other planet during the Imperial rule, before the Emperor dismantled the Senate. Preferably not about some big conflict like Rebels/Jedi vs. Empire/Sith, but just a story about ordinary people, like how not every Battlestar Galactica episode was about Humans vs. Cylons. But that would demand Disney/Lucasfilm stepping outside of their comfort zone and delivering something that will no doubt piss off some hardcore fans, so they will never do it.