Personally, I don't mind the increased price too much because it really is the only semi-pleasant way to get to LHR which doesn't involve a cab/limo service. (and as I travel alone most of the time, the HEX makes better economic sense)

The National Express buses are pretty unpredictable in arrival time... and the tube? Need I say more? For me the HEX is often a life-saver when I'm running late (as usual) and need to make it to LHR sharp-ish. The extra space and the stairs-less access is just a bonus.

I don't go on it as often as some of the others must do, but every time I have been on it the train had a good load so they must be (in the process of, at least) making some money!