The Keystep was such a big hit because it gave you more functions for your money by saving costs on keys.
A product of this price range simply can´t do everything.
If keys are your priority, you will always end up in the price range of a Novation mk3.
But for people like me, the reason why the sequencer and its capabilities are so important, is mainly because I suck at playing keys.
I find keys more intuitive, I find my way around scales and chords, I need them to get where I want to. So HAVING some kind of keys is a priority. Playing fast piano runs and being super-expressive on a nice keybed is not, because stuff like that will never come out of my butcher-hands.