It may be the instrument combinations. The combination lends a sense of avant- jazz freedom to the mix. The breaks he's smoothing out are, luckily, already seamless, but not perfect like some inane trance thump. Oiwa's not as adept at finding altogether new beat combinations as he is at finding familiar beats done in unfamiliar ways.
Acid jazz is only one of the many great vibes.
You may have respect for Icu because they know how to make songs like they haven't been made before. But even better than that is that these songs make you feel as funky as they want to be.