OP, I can answer this. It's because the movie's central message is that, if your life involves swords, magic, sex and heavy metal-esque music, you -- and your life -- are automatically awesome.
Look at Connor MacLeod: he's a master swordsman, women love him, he has magical powers, and his home in New York is basically a D&D nerd's wet dream. And wherever he goes, there's epic music playing.
Seriously... with that in mind, is there any wonder why teenage and 20-something geeks love Highlander so much?
Revenge is a dish best served cold. -- Klingon proverb
By all means, tell us what films you like. I was a kid when this came out and I love it to this day.
There aren't any movies that were made before I was born (which is probably your case with The Hilander) that I feel one bit disgusted with enough that I have to log on to imdb and rant about how silly it is.