They look really cool!...................
They do.
The main issues are:
(1) there are no windows aft, which creeps people out.
(2) most designs won’t work with current airport designs. You need ones that can get to a jetway that a 737 can also get to. (Any V wing, as proposed, takes two jetways — or the sides have to go one-at-a-time.)
(3) while inherently more aerodynamic and actually fly (as in “lift” or “glide”) better, they require computers to keep them stable, which also creeps people out.
I expect blended wings, in particular, to go first, as they are the most likely to work with existing jetways. They are also being built for business jets that will be in the market shortly — and don’t use jetways.