The Ropers moved in before Alton Towers was a theme park, back when it was only the house and gardens and possibly a few small rides so it's not their fault. (in fact I believe they moved there for the house and gardens)
I do thing they are being unreasonable because we city folk in London have to put up with more than just a few fireworks displays once a year and distant rumbles of a rollercoaster. I do understand it may be annoying if they moved ther for peace and quiet.
Also the other locals around Alton have said that they disagree with the Ropers (less large events = less business) so it is actually a case of a minority causing trouble because they can't put up with some noise.
Dave