Nice idea, but there's a big problem with that: The second is an SI unit. Changing it to a different value would require either an ugly fudge factor, or require changing the entire metric system. Either way metric depends on the second being the duration it is!
Thank you for that information. I did not know that. From our trustworthy wikipedia (http://en.wikipedia.org/wiki/International_System_of_Units): "Because the SI is not static, units are created and definitions are modified through international agreement among many nations as the technology of measurement progresses, and as the precision of measurements improves."
I'm sure they knew what they were doing when they agreed in 1967 to define a second as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.(http://en.wikipedia.org/wiki/Second) Though IMHO, it sure would be nice to be able to define a second as 1/100,000th of a day, something everyday people can grok. But of course, the "day" tends to change ever-so slightly in length each year. I can imagine people who need high degrees of scientific precision asking each other, "Are you talking about seconds in terms of today, or a year ago?"
But creating a calendar system has *always* been a big hassle with always a little bit of fudge factor. For everyday people, 1/100000th of a mean solar day would be fine, and it wouldn't make a significant difference to anything people regularly measure, even a 100m dash run this year versus 20 years from now. The Earth's rotation slows only about 0.002 every 100 years.