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).
Actually this is incorrect. Maintaining concentration is actually a Constitution Saving Throw, not an ability check. So hex wouldn't affect it. It is poorly named, I admit
Originally Posted by daMichi
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.
This is only half true. By default, 5e characters can jump up to their strength score if they move at least 10 feet, and 5 feet otherwise. Characters can jump 3+Str modifier high if they move 10 feet, and only half that distance otherwise. Since Hex affects ability checks, and not the score itself, hex wouldn't affect jump distance/heights in most cases. The DM can allow checks to jump higher or farther, but honestly I doubt Larian would spend effort implementing such an obscure and situational rule.