Do you really think Steve just let him do as he pleases to the point of firing anyone who argued with him about his design choices (see Scott Forstall, another man Steve relied upon)? Because that’s what’s happening under Tim Cook.Yep.
Steve saw him as the man to lead the design team. Right there is enough reason to believe on the guy.
Yes, he deserves criticisms here and there but his body of work is pretty impressive. I think most of Apple's issues (pro users lack of support) do not come out Jony but the overall direction of the company.