I guess the companies are focussing on what they do best. Take for example, Ety's, Shure's, UEs, and Westone's business model focusses on the IEM market while the others build their customer base with full-sized headphones. But I believe that the IEM market is growing, hence Senn's entry with the CX300.
I do agree that noise-cancellation phones are targetted at people who are not especially picky about the quality of music that they listen to. These people, IMHO, just want to get some "peace and quiet" during their journey. Coincidentally, these people are also those who have higher puchasing power. Hence the higher price =)