"Magic" is not necessarily something anti-ethical. Magic, historically, has just been the types of knowledge known by a minority of people throughout their society (which is why when we see the stories of magic that arise during Medieval Europe, when almost everyone was illiterate, the magic is tied to magic words, spellbooks and other arcane symbols whose meaning is known only to mysterious wizards).
Heck, the word magic itself comes from the Greek word for a Zoraostrian Priest, for the special knowledge the magi had that the Greeks did not. So consider: the inception of "magic" as a concept came from the knowledge brought down by one of God's Divine Manifestations.
Even to this day we have modern day concepts of magic, as in "unknown knowledge". As society advanced and began tinkering with chemistry, the notion of alchemy was considered a magic. Later we ditched the word "magic" but the widely exaggerated belief in the power of unknown knowledge persisted. Stories like Frankenstein and the many other tales of science creating horrible monstrosities show the next type of "magic" that was believed in, the magic of science. And in today's age... well, as a Computer Scientist, I can say from what I've seen in today's movies and media: The way you non-Computer Scientists view the powers of computers and "hackers" and the like is exaggerated and magical in and of itself!! Even the movies that try to portray computers realistically pretty much boil down to magic.
So are there problems with watching media that portrays "magic", or the old exaggerated ideas on the power of literacy?? Will there be problems in a distant, computer-savvy future with watching old movies like War Games which depicts our modern-day "magic" understanding of these boxes of logic circuits??
I don't think indulging in our past exaggerations are all that bad. I mean, for the most part, we as a whole know that "magic" as understood in the Harry Potter "magic literacy" context is not real. And the type of magic portrayed in Harry Potter isn't linked to anything evil (literacy based "magic" was the purview of European Scholars, the majority of which were devout clergymen, who got their powers through the study of Scripture and apocrypha (if anything, encouraging our kids to think they might learn magic powers from studying religion is a thing we might want to encourage!!), they were a distinct type of magic user from the evil wilderness-dwelling medicine makers who were feared as witches and who used magic not through books, words, and scripture, but with potions. Even though the word "witch" is used in Harry Potter, its "Witches" still use the word-and-learning based magic with Scripture-based origins). The Magic in Harry Potter even shows the origins of "magic" as "knowledge of scripture". Ever notice that most of the words they use for their spells sound like Latin?? The language of Scripture in Medieval Europe??
I actually think it is a bit more troubling to leave modern "magic" unaddressed. Seriously, the things people believe about the powers of computers is flat-out ridiculous. Modern day Hackers are as irrationally feared as much as olden-day witches. War Games is about a young apprentice wizard conjuring up a demon he can't control. Skyfall features the un-magical James Bond fighting against a magical warlock. CSI Cyber is about a group of wizards who use their magic to fight the magic of evil witches. There is little difference between our media's portrayal of computers and Harry Potter's portrayal of magic. We might want to acknowledge our current irrational belief in the power of unknown knowledge before we worry about indulging in stories of the long past irrational belief in the power of unknown knowledge.
Most people know that there are no words to give you magic powers, even many children. But pretty much everyone accepts the idea that you can do almost anything with the right computer codes. This commonplace distortion of reality is, I think, the one that needs to be addressed first and foremost.
Thinking more on this, a lot of magic has its basis in religious knowledge. Setting aside the more commonly known "magic" of old European religions, there are plenty of beliefs in magic with a root in Faith.
European Magic and its ties with Latin-speaking, literate clergymen I've already covered. The Greek belief in the power of Zoroastrian Magis and the knowledge they got from one of God's Prophets is also the root of the word "magic" itself.
The magic of the Medieval Islamic World is similarly tied to religion (when it is not tied to Djinni, that is). In the poem 1,001 Nights, there is a character who is a young girl with magical powers, who uses her powers to fight a djinn and save her father (I think it was to save her father at least, it's been a while since I read it). Her magic is from the study of Islamic and Jewish Scriptures, and instead of a magic wand she has a knife with "ALLAH" engraved on it in Hebrew characters. Once more, this is an example of scripture-based literacy magic.
Taoist Priests used magic through complex words written in a secretive language upon paper talismans, and was learned through studying Taoist Scriptures. Medieval Jewish magic was tied to learning words in Hebrew and studying the Torah and Talmud, even in the tale of the Golem, the magical clay construct, the Golem was controlled by writing Hebrew words and placing them into its mouth.
Magic, at least the "Abra Kadabra" word-based magic used in Harry Potter, has its origins worldwide in literacy and the study of scriptures. If you tell your children this true origin of the belief in magic, then I can only think of good things happening when they see magic portrayed in media. Maybe it will encourage them to read more.