Computers have uses beyond hacking. Guns are for killing. Killing in self-defense, honing your killing skills as a sport/recreation activity, deterring bad behavior by threat of killing, killing things that are socially acceptable to kill (i.e. game animals), sure, but the theme is killing.

Lockpicks might be a better example. Many similar arguments apply: their use is to open doors without the correct keys, which only a few specialized professions should have a legitimate need to do. Yet on the other hand we ought to be able to tinker with our private property, evaluate its security (bad guys will get lockpicks anyway), let ourselves in if we get locked out, publish security research on "unpickable" locks and participate in locksport.

Or for a more direct computing analogy, Metasploit. It is unambiguously a hacking tool, but it remains legal because bad guys will always get hacking tools, and the good guys need to be able to evaluate their defenses.