Yes hex is indded strange since it's meant to be a combat-oriented spell, thus affecting saving throws related to chosen stat.
I thought it will increase chances to hit with some spell effects like hold person (cursing Wisdom) or grease (Cursing Dexterity), but if hex only affect related abilities, most of all if not totally useless in combat, then yes hex is not really good ; +1d6 necrotic, wich is also not upscaled with upper level of the spell, and requiring concentration + a spell slot... meh.
That +1d6 is on each attack - once warlocks hit level 5 they should be able to Eldritch Blast
twice as one action.
