Direct hit is meant to be a dps only stat, but because it replaced accuracy it is currently on ARR and HW tank gear in abundance, so instead of locking the stat to dps like they did with piety and parry (stats that were primarily only on tank and healer gear) and going back to change every piece of tank gear that had accuracy on it to something else, they just left direct hit available to everyone and stopped putting it on their gear going forward. They obviously didn’t predict that players would value it over any other stat on tanks and healers so it became basically the only meld choice.

As for determination, the dps side is more potent than tenacity. Picture it like determination gives 100 damage while tenacity gives 50 damage and 50 mitigation. And since excess mitigation in this game is considered superfluous, determination is more valued due to it giving a greater dps increase.