Good question. It's the longest flights that are the most irritating, so the willing to pay may be higher. The example given on the Boom site of Los Angeles -> Sydney becoming 7 hours instead of 15 is compelling.
There is a point here. I am so used to travelling to and from Australia, that I find flights less than 7 hours to be annoying. You go through all he hassle of getting onto the dang plane, but don't have time to experience your flight in a relaxed, enjoyable way.