Fuck me, that's appalling. It's a bit of a "something is better than nothing" attitude towards booking.
A very cursory look at acts touring Europe at the same time next year yields the following results;
Green Day
Iggy Pop
Manic Street Preachers
Leftfield
Weezer
Yard Act
Idles
Bloc Party
Sisters Of Mercy
Ash
Spiritualized
Korn
Jimmy Eat World
Gojira
Kneecap
Asian Dub Foundation
Granted - only Green Day could sell out Musgrave Park on their own - but several of those bands are appearing at other festivals on the same bill - you could certainly cobble together a very interesting and higher quality one-dayer.
Better than the shit that is being spoon fed to audiences by MCD.