I don’t see the reason for having this affix on items, it removes attachment, is not that much fun and makes working for said items moot.
Unless an item severely tip’s the balance off the game, then it’s okay to zone restrict it, otherwise I really find no reason why such restrictions are there.
Why can’t I use my super fast Talbuk in MoP areas, it has 20 minutes cooldown, hell I’m okay with 60 minutes too. but just forgetting about these items / toys forever after you’re done with the zone really makes no sense besides fun detected, fun removed.
These items would also make world PvP much more wild and fun, unpredictable and creative, be it running for your life, or messing up your opponent with wild stuff.
And of course broken items can just be nerfed / restricted / not allowed.