We already convert simple URLs for the wiki into plain wikilinks. If you paste //en.wikipedia.org/wiki/Example into the link tool, the result is an internal link to [[Example]].

We should also do this for complicated links, such as //en.wikipedia.org/w/index.php?title=Example&action=edit&redlink=1

While that sort of link might be wanted on (rare) occasions, the 99%+ intention is to have a plain link to [[Example]].