Why would you not include the rest of the post where I addressed that part? 4d10 is not an average hit. The best damage fighter at 17th level will do 2d6+8 damage without an energy weapon (including +3 weapon) or 2d6+18 using Great Weapon Master with a -5 to hit. That is an average of 15 to 25 damage. Your average wizard single Fire Bolt will do 22 or 27 as an evoker. At the moment we don't know if they will have items to boost magical attacks. The Great Weapon fighter does quite a bit more damage per round than the wizard versus his cantrip. You can spike your damage with higher damage spells or spells that do damage with a bonus action.
Not sure why you would expect to do equal damage to a fighter with your basic magic attack, when the fighter is very limited in capabilities and the wizard is not. Fighter and wizard abilities are not equivalent. All the fighter has is his basic attack ability that he'll use over and over again. If they gave casters cantrips as powerful as the fighter's attacks, why play a fighter?
With Battle Master and Eldritch Knight, fighters have a lot more than their basic attack ability. By 17th level, the Battle Master Great Weapon Master with a +2 weapon (which I expect will be fairly common in most games) can do 2D8 (reroll 1s and 2s) +D10 +17 -5 to hit with advantage feinting attack for an average 30 points of damage and he can do it 6 times per short rest. Even after he runs out of superiority dice, he can still do it once per encounter.
Now, he can only nova like this once per round due to the bonus action. But still, if he hits with all 4 attacks (which would be fairly common against many foes at +13 to hit, not even counting advantages that the spell casters give the team), 15 15 15 30 = 75 points of damage. He probably will not be running into any resistance issues. And that's without other shenanigans. It will not be uncommon for a fighter to average 60 or more points of damage per round for a tough fight when the big guns are being pulled out.
Without a nova, the Fighter is doing 60 points of damage if all 4 hit (3 out of 4 hitting is probably going to at least be the norm).
The Wizard is doing 22 points of damage if his cantrip hits (3 out of 4 rounds hitting is probably going to at least be the norm).
So, the Fighter is doing nearly 3 times the damage of the Wizard.
When the Wizard novas for a round, he won't be using Meteor Swarm. That's not a power used in combat a high percentage of the time. He'll be using Chain Lightning (as an example) for 10D10 for 55 / save 27 points against 4 (6th level slot) to 7 (9th level slot) targets.
So, he is doing 220 to 385 damage (if all saves are failed). 3 to 5 times what the Fighter is doing when he novas.
At high level, it is not unreasonable for the fighter to be doing 3x the damage round in and round out, and the wizard doing 3x or more during a nova. The wizard only has 4 6th to 9th spells (plus Arcane Recovery) per day. He'll be doing smaller novas when those are gone. The fighter can nova a couple of dozen times per day with 3 short rests.
I don't think that cantrips should be as powerful as fighter attacks. I do think that low level cantrips should be less swingy.
