Drowning rabbits is a really EXTREME price for magic use. I don't mind Strange eating eyeball casseroles. It can be played for laughs. But I agree, why don't other magic users in the Marvel Universe pay any prices for THEIR magic use?
I think SOME rules for magic can create stakes in magic-based stories. You don't want readers/viewers to ask, "What can these people do?" and "Why can they only do it sometimes but not all of the time?" As other folks have mentioned, in Strange 2, magic sometimes worked and sometimes it didn't. If people can't have at least a general or even vague understanding of the powers being used in superhero and fantasy films/books, then nothing means anything. There are ZERO stakes. I think cause and effect can totally be applied to magic (if this happens then that happens).
I only started getting interested in magic in comic book storytelling AFTER watching WandaVision to be honest. After Slate published an article criticizing boring magic duels in Hollywood movies and shows. And I started wondering why can't magic battles be more creative and imaginative? Then I read about "magic systems" and understood why some writers/authors might wanna tone things down. I eventually stumbled upon a a blog entry by noted fantasy author NK Jemisin which aroused my curiosity regarding the debate over whether magic should "make sense" in fiction:
https://nkjemisin.com/2012/06/but-bu...to-make-sense/
The comments were EXTREMELY interesting to me. I thought Marvel/DC writers would be interested in the debates taking place in fantasy fiction circles in the past twenty years, and apparently Aaron is one of them?