Personally, I love the festivals...especially when it's some random radio fest thing in the middle of a regular tour so it costs the same but it's an all day thing with a bunch of extra bands. Mayhem was awesome and I'm not even THAT much of a metal head. Hell, if it weren't for festivals Manson would've never played with The Doors!
And just hearing Manson's vocal tracks for Skylar Gray and Lady Gaga even made Lollapalooza 2011 even better! Hopefully, he'll actually play it for real someday, I'd love to see that.
Plus, again, they pay for the headlining runs and all the big production stuff so the more festivals the better as far as I'm concerned!
:)