Brian Ashcraft:
K-On! originally debuted as a manga, and it then went on to spawn an anime, a feature film, and a video game. It's a pretty popular series, so when it's copied, people tend to notice!
The latest issue of Jump Next features up and coming manga. New comic "Ooedo Punk", which did get some good reviews online, sports some K-On! style eyes and facial expressions that match up with a still from K-On!.
This might be an all out copy, or it might be subconscious. Whatever it is, don't say "lazy".
It's already been established that it didn't rip anything off. Hyouka is animated by Kyoto which animated K-On. Move along.
Is this really an issue? The "manga" style lends itself very well to creative stagnation. Unless something is a trace of an action scene, or a clear copy of someone with a distinct art style, like Mitsuru Adachi and his fellow peerless mangaka, it's a bit silly to cry plagiarism at similar character designs.