There is a long list of design factors not being considered by the blended Wing/Fuselage design.
Designers tend to focus on one hurdle, in this case wing airfoil, and ignore all other factors as obstacles to achieve the one goal. They design this way, in part, because they know all other flight factors can be solved through the quick reflexes and responce time of electronics/ computer augmentation.
This is not unusual. The designers of the F-14 and V-22 ignored a long list of 'complexity related' design factors before production. Now they are both living with major operational difficulties.
A designers focus (airlines) is always on high altitude/cruise/smooth weather flight.
Design factors not fully considered a priority, albeit in-part for minumum 'acceptable' government certification, not a major focus of research or new technology:
1. Low speed flight control/lateral stability
2. Piloting difficulty/pilot workload
3. Manual overide performance
4. Turbulence/windshear behavior
5. Power plant/fuel economy (This is fully considered)
6. Crash /impact behavior
7. Airport manuevering/compatibility
8. Ground hospital/emergency capability in the event
100-500 or more passengers are injured at one time.
9. Operational/maintenance/parts/turn around time.
10. Passenger acceptance/attractiveness/looks strange
/looks dangerous (This is fully considered)