Even if he is, who was/is lining up for Bledsoe and Beverley? Smart and Bledsoe are clearly higher ceiling offensive players. The former is a good secondary play maker and decent shooter, while the latter is a good slasher and finisher.
If his offense takes another jump, it'll merely be in the vicinity of average. His shooting, though clearly improved, was small sample size and wide open. He's nowhere near being able to puncture defenses in p-n-r or space the floor.
He's a problem because he doesn't have value, which means stubbornly retaining him as opposed to giving up away. The money in a vacuum isn't a big deal, but he's a difficult piece to build around and because they jumped the gun on him, they might be less likely to extend White now (lack of durability doesn't help) or if they do, they'll have tied up significant money in a backcourt severely lacking in offensive dynamism.