Brian Sanderson (and others) have written plenty of magic-filled books with more interesting endings. If you want a 'hard magic' system, the one in the Mistborn series is pretty interesting (ingesting and 'burning' particular metals for particular abilities):

* https://en.wikipedia.org/wiki/Mistborn

* https://en.wikipedia.org/wiki/Brandon_Sanderson

'Booktuber' Merphy Napier recently did two videos on magic systems in fantasy novels:

* https://www.youtube.com/watch?v=WcMQk4ltJa0

* https://www.youtube.com/watch?v=Nd6f3tAOUHk

Brandon Sanderson*

Sanderson has lectures on a system of rules for magic in books to balance their coolness against deus ex machina: https://stormlightarchive.fandom.com/wiki/Sanderson%27s_Laws...

That's not an excuse for sloppy writing though. Even a book about magic needs a level of consistency within its own universe and when the quality is above a certain level, I'm prepared to suspend disbelief and go along with the story and not nitpick.

It's also a children's book that evolved in a book for young adults. I always thought it was supposed to be whimsical and fun, not have serious complicated plots