Zeitgeist

the French revolution was an era of extreme political
and social change. Revolutionary fervour was applied to time
itself. For a brief period, the French Republic introduced a
decimal time system, with each day divided into ten hours
and each hour divided into one hundred minutes. It was thoroughly
logical and clearly superior to the sexagesimal system.
Decimal time was a failure. Nobody used it. The same could
be said for XHTML 2. The W3C rediscovered the lesson of
post-revolutionary France: changing existing behavior is very,
very difficult.

Excerpt from HTML5 for Web designers


This is something we must keep in mind.