Is this alteration to the Evocation Wizard’s Potent Cantrip balanced?

The Potent Cantrip ability states:

Starting at 6th level, your damaging cantrips affect even creatures that avoid the brunt of the effect. When a creature succeeds on a saving throw against your cantrip, the creature takes half the cantrip’s damage (if any) but suffers no additional effect from the cantrip.

This seems to limit the wizards choices, as there is no benefit of this feature to cantrips like Firebolt or ray of frost. My alternative proposal is this:

Starting at 6th level, you add your Intelligence modifier to the damage you deal with any wizard cantrip that does not already add an ability modifier.

There is precedent to adding an ability modifier to a cantrip, as seen in the Cleric’s Potent Spellcasting or the Warlock’s Agonizing Blast. The additional "…that does not already add an ability modifier" is to account for spells like Magic Stone or Booming Blade, so these cantrips would not stack modifiers. The main reason I feel this may not be balanced is that this ability is given at 6th level, as opposed to the Cleric receiving it at 8th level.