Nathan Chen was a very musically adept skater. He played the piano & he had ballet and gymnastics training, and it showed. As Kurt Browning once said, "Nathan Chen does not skate like anyone else" who came before him. I agree. Nathan brought his own unique style, and with the help of his choreographers, he ushered in a new way of expressing one's personality on the ice, which had a significant impact. This, in addition to his multiple quad expertise and technical efficiency. For sure, he wasn't perfect in every aspect, e.g., not having the best flow out on his jumps. But, with the help of coach, Rafael A, Nathan was one of the best strategists in terms of laying out his jump placement and pacing himself over the course of each season.
As Chris Howarth said in his recent coverage about both Nathan and Ilia, 'their strengths are mental focus and innate confidence,' or words to that effect. As far as Ilia's artistic abilities, I think he's still exploring what he can uniquely accomplish on the ice artistically, while wielding the expected multiple quads, which he makes look so effortless. At this point in time, it appears to me that Ilia is moreso competing against himself, while of course keeping an eye on the rest of the field. But it's largely about challenging himself to safely navigate new heights. He's certainly proving that he doesn't need to compete with the quad-axel every time out in order to dominate the field.
In regard to having artistry, Ilia clearly has artistic abilities which he displayed in his beautiful performance at the Legacy on Ice tribute. It's just difficult to fully concentrate on effectively incorporating aesthetic nuances while consistently executing multiple quads in high-stakes competitive performances. He is certainly trying to forge a creative path with the help of his choreographers, but he's not doing it in ways everyone likes or agrees with.