There is an increasing use of soft hyphens (­) on the web, which makes senses from a responsive design POV.
Regular Wikipedia users are used to copy-paste terms from websites and just prefixing it with the corresponding wiki url (like "http://en.wikipedia.org/wiki/").
However if a term containing a soft hyphen is copied, this does not work as expected.
Instead users will be flabbergasted as to why there is no corresponding article and may be even tempted to create one (especially, since neither the browser address bar, nor the Mediawiki "page not found" site will show a visual indication of the errand soft hyphen).
e.g. compare
As I see no practical use case for allowing ­ and other non-printable characters in titles (as was already discussed in T5696 and T121979) I suggest to redirect users that attempt to visit a path containing such a soft hyphen to a trimmed version of that path.