It is not the fantasy that's dangerous. I'm not saying people shouldn't read Harry Potter, or that they're going to become possessed for enjoying it. But if you really can't see how exposing children to fiction which explicitly paints the occult in a good light can't possibly open minds to dabbling in the occult later down the track then I'm sorry, but you're being wilfully blind. The entire premise of the story is the occult (a fictional and fantastic idea of it albeit) in ways that is simply not the case in Lord of the Rings.It is entirely baseless. It's no different than saying the Lord of the Rings, Sword in the Stone, or Wizard's First Rule is going to draw people into the occult. And I think it's pretty much understood and accepting by everyone except the Conservatives saying otherwise that Harry Potter is nothing more than a fantasy that brings in creatures and settings and character archetypes that have been a part of our cultural stories for hundreds or even thousands of years into a modern age (modern at least when they came out - the world has changed much since then).
I don't share some of the more fantastical concerns about Harry Potter, or pop-culture in general. But I perfectly understand a Christian parent not wanting their children being exposed to stories which explicitly paints the violation of the first commandment in a good light. I also understand parents not wanting their children exposed to music and artists whose themes are overwhelmingly negative and in some cases explicitly anti-Christian. An open arms embrace of pop-culture as being utterly benign is naive, (especially for Christians) as is an unreasonable and exaggerated fear of it.