I occasionally see Maiden on Much Loud. Aside from that...let's see if I can find an old post of mine.
Nope. I can't.
Here's the basic. Metal is not on TV because it is unpackagable. MTV and other stations make their money from advertisements. Consider the amount of skill it takes to run a successful metal band. Consider the amount of talent it takes to even get close. Look at it this way.
Let's say 100 people watch Iron Maiden on MetalNet, our fictional metal network. Of those 100 people, 75 like Maiden. 50 are interested in playing music like Maiden. However, only 20 have the necessary talent. Now, let's assume that their talents are divided like so: 4 drummers, 4 singers, 4 bassists, and 8 guitarists. What is the likelyhood that these people will meet and form a band? Not very. Now, what's the likelyhood that these people, if they do meet and form a band, will actually cooperate long enough, practise hard enough, and work hard enough to become famous? Nil. So, let's give them the benefit of the doubt, and say that one band forms from these 100 fans.
Consider grunge. Using the same base 100, in which 75 like the music and 50 want to play, the talent requirement is lowered. Let's say 30 people. Now, you need less people to form a grunge band, and you need less ability to play. This transcends into less practising. So, you get three or four bands with this formula.
Consider pop. With the same formula, the talent requirement is lowered. Now, all you need is decent good looks. So, basically any combination of 3-5 people could form a pop band. Stunning looking people can go it alone, because the voices are digitally altered, and the songs are written for them.
Rap has the same formula.
Now, look at it from an MTV exec's point of view.
Metal: 1 new band looking for advertisment space. Kinda blah.
Grunge: 3-4 new bands looking for advertisement. Getting better.
Pop & Rap: Wow, something like 20. Hot! We've just hit the gold mine.
Well, since most people are sheep, and do what they're told by TV, if we shove pop and rap under their nose, we'll get a huge upstart of people wanting to be pop stars. And since the record companies think the same way we do, they know that we'll sell them tons of records.
HOLY SHIT! Let's make TV shows based on becoming a pop star! Instant advertising that people want to see! FREE advertising for the record companies, and AWESOME payouts from commercials! Holy shit! We're gonna be fucking rich!
That is why metal is not on TV.