I remember reading about MSX in Creative Computing magazine, there's also 4 pages devoted to it in the book Digital Retro.
In addition to the reasons listed here I'd say that what killed MSX is what killed everything else back then, the rise of the PC compatibles. In the early 80's there were "personal computers" based on 8-bit processors that were for the home hobbyist, and the IBM PC-type computers that were so expensive that they were mainly owned by businesses. Basically everyone wanted the PC compatibles to run all the available software, so when prices came down no one wanted the 8-bit Z80 and 6502 machines anymore.
In addition to the reasons listed here I'd say that what killed MSX is what killed everything else back then, the rise of the PC compatibles. In the early 80's there were "personal computers" based on 8-bit processors that were for the home hobbyist, and the IBM PC-type computers that were so expensive that they were mainly owned by businesses. Basically everyone wanted the PC compatibles to run all the available software, so when prices came down no one wanted the 8-bit Z80 and 6502 machines anymore.