Most consumers don't think about security beyond enabling a lock screen. Average people do not think twice about promiscuously plugging their devices into any ports they find. This attack vector is entirely off their radar. On the other hand, gadget purchasers care deeply about sleekness. Based on reactions I have witnessed, I suspect some people may even be sexually aroused by gadget sleekness. Therefore, at this point there is little incentive for a company to sacrifice their product's sleekness for a security enhancement. Until typical customers start caring I do not see a split-port solution happening.