I agree they didn't need to add the alien storyline, but I liked the mysterious and somewhat light-hearted conclusion it was given. I thought it was handled well.
As for being gross just for the sake of it, that's exactly how I felt about season 3. What an awful season. Bleh. Just thinking about it makes me sick. I will say this though - season 3 undoubtedly had the best opening theme. When I saw that opening theme with the witches in the black KKK-style robes, I thought "Holy ****, this is going to be the most horrifying season yet". Boy was I wrong.
Despite season 2 being the closest to a real horror story (imo), I don't think any season has actually been scary. The opening themes are so atmospheric and full of terror, but the actual shows are very disappointing in comparison.
This Freak Show circus/clown concept doesn't interest me at all really. I hope that we'll get a proper alien abduction story as the main focus of a season. I'd also love to see their versions of Frankenstein, vampires and werewolves (1 season for each).
I don't want to give up on this show because I love the idea of it. The quality just isn't that great for the most part it seems.