If explainable AI is too limiting, what's the alternative? What's going to happen when someone gets hauled into court to be held liable for their non-explainable AI's outcomes? Oh right, I know, they'll hide behind corporate limited-liability shenanigans, until people get tired of that and go straight for the guillotines. Or maybe the non-explainable AI's owners will decide they want to prevent that, and ... do you want Skynet? Because that's how you get Skynet. Maybe spend some time thinking about the various awful ways this could play out before concluding that explainability isn't important.