You obviously didn't play as a Warlock, let alone have two in your party. Hex is a CLUNKY TIME-WASTER as currently implemented. It is a spell you cast/re-apply nearly every turn as a bonus-action. The secondary curse effect has little to no in-game effect, yet we have to got through a menu to manually select an attribute to curse. These are the things that begs for STREAMLINING homebrew!
Simply make the secondary curse effect curse ALL attributes AUTOMATICALLY (Warlocks nerfed relative to other "full casters" by near unrestricted access to long rest and could do with a little buff anyway). If for some reason this is seen as overpowered, simply balance disadvantage with a smaller flat penalty to all attributes. Combat has been criticized as too slow-paced, and this *will* save a lot of time and annoyance.
I would prefer they leave Hex as it is in 5e but I can right click on the Hex spell in the UI and it is then set to "Auto-mode" and always automatically uses either the highest ability of my enemy or the stat with what the enemy is fighting, e.g. Dex for archers, Str for two-handed fighters, etc.
That may sound like the best of two worlds, but still miss the mark as well as add largely needless complexity to the game.
It doesn't normally do much of anything to curse the highest attribute, nor highest attack attribute. For instance, cursing Intelligence or Charisma of Wizards or Sorcerers likely has no in-game effect whatsoever.
Skill checks are not opposed by NPCs in the game as far as I know (Shove being possibly the only exception), so I suspect it's completely useless out of combat/in social settings.
Some possible scenarios where I think cursing attributes may conceivably have any effect at all:
Strength: Very limited usefulness. May be useful if you plan to use Shove (and the enemy has better athletics skill than acrobat), or if the enemy can Jump and you use Hex as an opener before they actually get to jump. Hex as an opener is a very questionable move as you aggro the enemy for little effect.
Dexterity: May again be useful if you use Shove (and the enemy has better acrobat skill than athletics). Since initiative order is rolled once at onset of combat, it won't affect initiative unless used as an opener (before rolling initiative).
Wisdom: No usefulness. Total trap option.
Intelligence: No usefulness. Total trap option.
Charisma: No usefulness. Total trap option.
Constitution: No usefulness. Total trap option.
Unless I'm missing something significant, and please correct me if you think I am, then having the option to curse specific attributes is purely a waste of time in the VAST majority of cases. It stands to reason then that streamlining the curse secondary effect to automatically affect all attributes is the most sensible method, and that having Hex give disadvantage to all ability checks isn't even remotely unbalancing in the context of BG3.
Hex Constitution would have a benefit if concentration would work correctly and can't just be broken by using create water + frost ray cantrip to make a caster go prone (aka incapacitated).
Intelligence would be nice if a enemy caster then could fail an Arcana check and would not cast shield as a reaction because they don't recognize that your wizard is casting a blast spell (a little bit far fetched, i know, and not covered in DnD 5th RAW).
Jump should be used as part of movement, not as a (bonus) action, so hexing Str should only have an impact regarding how high a character can jump.
To set things to a kind of automatic mode is just a suggestion. Take any spell, e.g. magic missile, right click on the spell in your hotbar and a moving, glowing border appears. Then you e.g. always use your highest possible spell slot. Or you see a drop-down menu, were you can set a standard option.
