It's certainly not brand damaging, it's not a good ride agreed but as far as I am aware it goes down well with the GP and therefore good for the brand.
More importantly, FOP is great but its not some ground breaking experience as far as I am concerned (I'd even argue F&F is actually more or a ride...) and ROTR and Mickeys are not even open yet how can we really compare?
Have you been on Hagrids?