To me the biggest risk in any product is not getting the right product out. Quality comes second. Iterating rapidly allows you to get to the right product. The impact on quality that comes from not having enough time to think through design, code and test, in theory, could be compensated for by "smarts". To the extent Agile helps iterate to get to the right product it is valuable. The specific mechanics of it are not "nature laws" and hence should and must be changed by smart people to see if it fits their purpose.