I mean, every single time you gain a new spell level, most cantrips go up an extra die in damage value. That 1d4+mod cantrip is 2d4+mod at level 3 and 3d4+mod at level 5. And keep in mind, you can crit on Ray of Frost for double damage.
That doesn't seem that bad.
I think that eventually cantrips get better. They're not horrible at the start (though under where a fighter is), but because they're less effective than a fighter's regular attacks, I want the first-level spells to bring up the effectiveness of the wizard. If a first-level spell is on par with what the fighter can do normally, that's not impactful enough.
Remember: Vancian casting! You've got two spell slots (plus you can reuse one spell with Drain Bonded Item), which you prepare with EXACTLY the spells you'll cast.
I can't see any magic items to increase the effectiveness of cantrips, btw, nor wizard abilities.
Trying to work out how the fighter scales is an interesting matter. It's no longer "you get extra attacks at high levels", so we have to look at other abilities.