And again I agree. What they failed to fully see is the emotional connection people have to the brand. (I also think if they had reduced the price in proportion, the result might have been different).
In fact, if JD had made the change from 86 to 80 today, it might have been the same for them. I think they got in under the wire on this, at a time when Facebook and Twitter feedback (in particular) was much less developed.