They just don't really fit with Bloodstock's typical subgenres of choice (power, thrash, black, death, folk, symphonic). If they were headlining based on their pre-Holy Hell stuff they still would have been controversial but based on their last two albums it really feels like a stretch too far, they're just not really heavy enough for Bloodstock anymore. A lot of Bloodstock's core audience don't want the festival to just be a mini-Download, they prefer it to be focussed on the more extreme or niche stuff.
