I have no prob with standard song structures, but I don't think they work well in Power Metal - I think they work well for pop. The Beatles early material was all extremely standard, but because the songs are so cleverly written and so catchy those songs are incredible. When it comes to power metal though, I don't think the goal is so much to appeal to the widest audience possible and be instantly catchy. All metal thrives off emotion and drama. I liken it to film score in terms of exploring varying moods and implying actual events with harmonic decisions. I find when power metal tries to be standard it's like less effective pop. Especially dealing with power chord progressions - at least pop uses more interesting chords and progressions, by comparison these neutral power chords bopping predictably about the minor scale is intensely uncreative.