Beyond the complexity, I really like how DCC turns pretty much every spell into its own adventure hook. You could spend a session just dealing with the mishap roll on a spell.
The other system I'm aware that does something similar is the ritual spells in Beyond the Wall.
I like the Idea of DCC magic, the misshaps, the chaos, I would read a novel about Wizards casting that. But has anybody here ever played a DCC Wizard?
Because that sounds exhausting to play for longer games.
But for magic -
I would prefer for D&D more differentiated casting times and better rules to counter/Interrupt spells.
So, I would add an additional casting time of "till the beginning of your next turn" - so as an action you Start casting your spell on your turn and finish the casting, when your next turn begins.
And I would turn all the strongest 1 action spells on to that casting time, like fireball. You still have quicker spells that you can cast as an action, but the more impact full the spell, the longer the casting time.
What that does, is that it is an announcement of what is about to happen next round.
And now everybody can also try to interrupt the caster (like you can interrupt a spell with a casting time of a minute by attacking the caster, that forces concentration checks).
Now suddenly we have a more tactical dimension of the game. Protecting casters is now important. Now players and monsters can make tactical decisions, based on what the casters do.
I would also add such longer casting times to special monster attacks like dragon breath weapons.