Ellsworth Kelly unquestionably has a place in art history. I was never excited by his work. I felt it made sense and has relevance in its timeframe, that is, in the step by step linear history of art and the development of abstraction and minimalism. But beyond that, it felt repetitious and nothing more than variations on a theme. When he breaks from the simple geometric shapes painted a color (blue square etc) and "pushes" a bit - using organic shapes, juxtaposing shapes and colors, channeling Matisse and Rothko - those pieces are much more interesting, IMHO.
Although brief, this video of EK talking about his work is insightful. I find his earlier work with shadows, like the painting in blue of parts of shadows based on his photo of the stairs (seen in the video), to be far more intriguing than a black square or yellow rhombus.
Even at his age, it's wonderful to see an artist still jazzed by painting and his personal visions.