The Pokemon anime absolutely peaked during Kalos, specially during the league and Team Flare/Zygarde arc. The ratings objectively skyrocketed and its social media presence grew a lot. Many of the videos that have been uploaded to YouTube containing its opening and memorable scenes got millions of views, most notoriously this one
https://www.youtube.com/watch?v=CQuObfTx6Cg with more than 8 million views. Whether you like Serena and Kalos or not, it is factually wrong to say no one cared about gen 6's anime; it experienced a renaissance of sorts after plummeting with Black and White. I'd even say Kalos did better than Sinnoh as far as reception and popularity goes.