I know that Bungie doesn't want OHK grenades, but I think it should be allowed when wearing specific exotic gear. Afterall, Warlocks already have a OHK grenade in the form of Handheld Supernova.
Exotic gear such as Ashen Wake, Lucky Raspberry, Young Ahamkara Spine, Shinobu's Vow, and Starfire Protocol.
This would make multiple builds in the crucible more viable.