If Smith had conspired to do the actual hacking of Clinton’s server, that would be a serious crime. If the Trump campaign had joined such a conspiracy to commit hacking, that would be a true scandal. But if the goal was simply to obtain information that some independent actor had already stolen, and then to use that information to the detriment of a political opponent, that is fair game—and happens all the time.
As it happens, there is no proof that Trump campaign officials were actively involved in Smith’s project. But it wouldn’t matter if they had been. In fact, it wouldn’t matter if there had been no Smith at all and Trump himself had put a full-page ad in the Wall Street Journal, encouraging anyone, including Russian hackers, to send along any emails they might have hacked from Hillary. As long as Trump was not complicit in any theft and merely wanted to acquire and use information damaging to his political adversary, that would be politics as usual.