My own fix is just reduce all ki costs of four-element disciplines by one. But I like your idea to give the four cantrippy ones away for free, too.
My issue with the Way of 4 Elements monk is to look at the Eldritch Knight, Arcane Trickster, and all of the Paladin subclasses.
Each of these learn new spells that use their spell slots (EK and AT gain spell slots, but the Paladin doesn't) on top of gaining other abilities.
All the Way of 4 Elements monk gains is new abilities that use their ki.
If Ki translates to Spell Points, which it does for the most part, then the costs are okay, but nothing else really comes with them.
The Way of Shadows monk learns some spells, and a cantrip, as one of their features, but the costs on the spells are lower than for the Way of 4 elements monk.
The Sun Soul monk learns burning hands at one of their levels, but it's a bonus action, so it has value. They also get a radiant fireball, but it's at-will at base, so it has value.
The way of 4 elements monk needs some class features. For instance, at some point they should be able to use their spells as a bonus action. This would be comparable to using Flurry of Blows and balances out at a glance.
After thinking on this thread for a while, my big issue with the Monk is how integral Stunning Strike is to their combat effectiveness. I'd rather stunning strike cost more, be more risky, but also be rewarding, and I'd like to see an Improved Flurry of Blows and some type of combat damage bonus at around level 11. The monk starts off as a very solid damage dealer, on par with the rogue, but falls behind in damage and becomes more of a controller at high levels. This is cool, and it's good to be different, but changing the role on a character without the player choosing is frustrating to me.
