I don't want this to descend into another "West vs East" thread, but the undeniable truth is that the west is severely lacking in it's animation variety. The shows that usually premiere to western audiences are either children's shows (which, granted, can cover mature themes and topics, but they're inherently limited in their expression of those ideas DUE TO the fact that it's for kids) or raunchy, vapid, low budget comedies. There is a very severe lack of shows or series that are intended for a mature audience that takes itself seriously and tries to tell a cohesive, semi-thoughtful story (such as if The Walking Dead was an animated show in the style of the comic books instead of live action, for example).
Some will say that it's due to America's idea that animation is for kids, which is understandable, but there seems to be SOME kind of market for this type of animation regardless, as evidenced through the semi-mainstream popularity of anime such as Attack on Titan and Tokyo Ghoul (less so for TG, to be fair). Maybe I'm just a brainley, but it kind of baffles me that NOTHING is really being made for that market, and I want to know why.