There is a whole journal devoted to origins of life studies ranging from experiments similar to the Miller-Urey experiment to completely different from these experiments. The journal is entitled "Origins of Life and Evolution of Biospheres." Other experiments have been reported in journals like Science and Nature, Geochimica et Cosmochimica Acta, the Journal of Molecular Evolution, and Astrobiology. I believe that a bibliography of experiments related to origins of life studies (presented in the journal Origins of Life...) from the early 1980s listed about 1000 papers on this subject. Since then, the field has continued to grow.
I would say that your textbook is neglecting these experiments mainly because to discuss them in depth would require a full class on its own. That's not really possible, and not really necessary for understanding general biology. The Miller-Urey experiment is commonly quoted since it was one of the first experimental evidences for the production of organic compounds, and it was one of the easiest means of producing organics. The book is likely just discussing the key experiment that laid the experimental framework for many future origins of life studies. I think it's probably akin to discussing Darwin's finches as evidence for evolution.
It is probably true that your book should have a follow-up sentence along the lines of "Experiments performed after the Miller-Urey experiment have further confirmed the production and chemical evolution of organic compounds through abiotic means." Still, textbooks aren't easy to write, and the authors aren't origins of life researchers.
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