Is heavy metal concerts allowed anyway in Malaysia? 

Coz there are so many big bands (Dream Theater, Helloween, Iron Maiden, Stryper, Metallica, Yngwie) already came to other countries in the region, most notably Indonesia but yet they always passed on Malaysia. Here we only get pop rock stuff like Bon Jovi.    So I'm wondering is there maybe a regulation that prevented metal bands to come here (that will be a big shame if true) or we just don't have enough market hence not attractive for them to come.

Oh so they get much scrutiny then.    Actually those artists that promotes more offensive stuff or sex are mostly pop and rap artists. Even their clothing and dance movements are so sexy.
Bands like Dream Theater are not having any offensive lyrics and shows actually.
Stryper actually is a Christian Metal band, but maybe that;s why they will never come to Malaysia despite them had a very successful show in Indonesia.