I never liked systems where magic was just something indescribable that could do anything the plot needed it to do. The best magic systems are ones with clear, and consistent rules. Where it has defined limitations, and situations where it can and can't help, and specific people who can only do certain things. While magic is certainly very useful to hand wave some things, it should, at the very least, make sense! Perhaps the intricacies of magic will never come up in game, but even if it never does come up, us knowing the system helps us make sure that any time magic does get used, it's in a logical and lore-friendly way!