Those of us who enjoy listening to metal music have noticed that our favourite musical genre tends to be rather...underrepresented, at least as far as radio stations are concerned. The DJs will play love song after love song after sappy love song, but no matter how patient we are, they never seem to cut loose with a metal ballad. Why is this?
Music, like any other medium, is the product of the person who created it. Naturally. However, this has an important implication: the person creating their work has an emotion which they wish (and in fact, may even need) to express. Many of the songs on the radio today are either the aforementioned love songs, or about how happy or sad the artist is. There's a mentality here: either we should express our inner happiness or sadness, or we, as romantic/sexual beings, should celebrate relationships.
How does this relate to heavy metal? Simply put, metal bands have a completely different mindset. Rather than focus on relationships (although sexual imagery is often rampant) or happiness and sadness (again, joy and sorrow may factor into the lyrics), metalheads like to sing about things which are relevant only to themselves, if even that: there's a reason Horrible History Metal and Mad Lib Metal Lyrics exist. In other words, it's not what the song is about so much as what it sounds like. This isn't universal, of course, but metal musicians are far more likely to have this mentality than others.
Conversely, metal tends to be a lot more artistic than other musical genres. Imagery includes battle and glory, quests for honour, lost lineages, voyages to far-off lands, etc. It stands to reason that metal is also more cerebral than other genres; in other words, most people are less likely to appreciate it.note