Keys are annoying. You accidentally drop them in the water while harvesting clay and then you're fucked. You can't get back into your place because you've accidentally destroyed your key. It's like one of those really heavy nights out where you're pissed off your face on booze, and accidentally lock yourself out of your house. Except there's no booze, which makes it less thrilling.
Make kin able to open and close the gate that you've build, in exactly the same way claims allow people on/off your property.
We already have the mechanics in place (claims). Uh, maybe make it so you can still use the key for those in the playerbase who gain masochistic pleasure from accidentally destroying their keys and being locked out of their land.