Well as you said Asylum didn't have as much of a main plot - at first it was Bloody Face, then it was Lana's escape, then it was the shut down of Briarcliff. And all of the other plots tie in to one of those three things perfectly. And they're all interesting.
You're right, the plot of Coven SHOULD be the coven, but it isn't. It's about who's going to be the Supreme. They've barely even delved into the existence of the coven before Zoe arrived. That's why it's boring and why most of the side plots don't tie into it.
There is NO character progression in Coven. Getting more powers isn't character development, that's just a plot change. A character's personality developing is character development. And barely any of the characters have changed at all since the first episode.
How have we not looked into the existence of the coven before Zoe arrived when there have been flashbacks of old rituals and Fiona's early life in the coven. Plus, a show has to start somewhere and with we need to start following their life from a certain point, in this particular example, Zoe's arrival.
geemarty already showed you a list of character progression so there's nothing really that you can say in order to say that this is a bad season, only the fact that you personally don't think it is, but that's a preference.
Zoe: Went from quiet girl to a zombie warrior princess in a matter of episodes. Then turned into a strong female confused over whether to side with her Coven or leave and choose love.
Nan: Went from have no confidence to being as confident as can be and killed.
Queenie: Went from hating the whole sisterhood and not feeling accepted to joining the Voodoo and ultimately feeling confused over where she stands.
Delphine: Went from racist to slightly racist to back where she started.
Marie: Went from thinking she was untouchable to realizing she wasn't.
Fiona: Went from Power bitch to dwindling senior who thought she had nothing else to give. Then to have her fight re-ignited by Spalding.
I could go on.. but just because you say there isn't any character progression doesn't mean it's true.
None of them are really that noteworthy though. They're all slight changes (perhaps with the exception of Zoe although she's just an uninteresting character) or just realisations, not character development. No one's progressed like Sister Jude did in Asylum, or Ben did in MH.
I really enjoyed the latest episode. I Hope the Supreme ends up being Cordelia just because it would kill Fiona. It would be a fitting end for her character.
New Mexico/Area 51 could give even more options than JUST aliens.
It could include any of the following (a website posted these)
Sci-fi, Aliens, Nuclear Testing, Radiation, Mutations, Circus, Communism, McCarthyism, Cold War, Utopia
Okay, if the examples I previously listed weren't enough to show the lack of character development:
The coven finds out FIONA KILLED MADISON AND FRAMED MYRTLE. And they're sipping ****ing tea with her after their failed plan. Come on? I love this show, but it's like a sitcom now. Anything that happens just gets re-done and they all end up in the ****ing house again.
I've been wanting an Area 51 season since Asylum I would be ecstatic. Although anything about aliens will make me happy. They're such an interesting topic.
The flying saucer lights/men in black/theremin are basically confirmation that it's about aliens.
Okay, if the examples I previously listed weren't enough to show the lack of character development:
The coven finds out FIONA KILLED MADISON AND FRAMED MYRTLE. And they're sipping ****ing tea with her after their failed plan. Come on? I love this show, but it's like a sitcom now. Anything that happens just gets re-done and they all end up in the ****ing house again.
Mess. How is that a lack of character development? That's you not liking the writing and where they took the story. There's a difference
Area 51 would be so good 
