I think I recall them saying they wanted to focus on more action-oriented shows instead of giving it another season, but I didn't really see much from them in that regard. Honestly, The Knick felt so out of place on Cinemax, it should have been an HBO show.
It was so weird too because The Knick was the only thing Cinemax ever aired that wasn't some kind of pulp action/thriller/crime show.
Even if Soderbergh wanted to be the big fish in a little pond at Cinemax, they should have moved the show to HBO for future seasons after it was deemed to be incompatible with Cinemax's audience.