Chappie was by no means a horror movie, but scifi films share a common ancestry with the horror genre. The further back you go, the more the lines blur between the two genres. Neill Blomkamp doesn't bridge this gap as well as, say, Ridley Scott, but he does bring his own vision to scifi that occassionally pays homage to the disturbingly violent set pieces of other scifi/horror films.
Blomkamp has often referred to his first three films as a "trilogy" of sorts. District 9, Elysium, and Chappie were all films with political and social commentary. They seemed to drop in the tone of this commentary with each new piece, closing out with a far less direct attack on your conscience. Chappie was a piece that was more for fun than it was trying to make a statement.
It is becoming a common theme amongst critics and movie patrons alike to consider Blomkamp a one-hit-wonder, with the reception of each of his films dropping in successive order. District 9 earned Blomkamp the freedom to pursue his work further in the original scifi genre. The less successful "sequels" have already tarnished two reputations: Blomkamp's financial benefit to producers and the profit that can be found in original scifi cinema.
While I hate Blomkamp's films far less than most (I can still appreciate a fun story, fantastic visuals, and great set pieces despite poorly fleshed scripts and choppy directing), it is the frowns on producers' faces towards future scifi films that disturbs me. Unlike the horror genre, which has always been forced to adjust to relatively small budgets, scifi films can often explode onto the screen. It is sometimes able to manifest fresh ideas where horror must simply allude. Films like Cruise's Oblivion (admittedly not great) and Edge of Tomorrow (NOT called Live. Die. Repeat...seriously, that confused so many people...what a poor cover design) just simply didn't perform well enough to encourage more films like them.
Many people might disagree here, but sometimes it's a good idea to support your favorite genres even if a particular film doesn't appeal to you. You never know what your support towards visionaries like Blomkamp means to the future of the genre. Chappie wasn't great. It wasn't garbage, but it wasn't great. I will never regret seeing the film. Nor do I regret Edge of Tomorrow, Oblivion, Prometheus, or the countless horror films I take a chance on. Sometimes it's not about supporting a particular film, but supporting the genres you enjoy. Because, let's face it, the big-wigs will stop throwing money into the pond if the fish quit spitting change back. And I don't want those big-wigs to get bored with my pond.