STR/MND/INT/DEX etc all fundamentally achieve the same thing (contributes to AP) to their respective roles. What SE should've done was simply create a new main stat for tanks that simulates what STR does now, then replace STR with it on left sided gear, and VIT on right sided pieces. If they're still worried about HP at that point then either adjust the level of incoming damage, make this new stat also provide HP (but not as much as VIT), or make the new stat improve Tank defences.