Why isn't the market open 24/7?

Anyone who's traded stocks more than "infrequently" will know that the markets are open between 10AM and 4PM. Presumably these hours were selected many decades ago to allow stock brokers to arrive at a reasonable hour, and get some preparation done before the market open.

But in this day and age where the Internet allows us to buy things any time, day or night (from anywhere around the world), why is the stock exchange still restricted to these archaic hours? Thanks to online brokers such as CommSec, many investors nowadays are private investors, with full-time jobs that don't involve securities trading. And many other investors are even in different countries, in different timezones.

A 10AM-4PM restriction is not only inconvenient, but it just doesn't make sense anymore. It's not like the technology doesn't exist; the ASX already has a computer-based trading system.

A market that's open 24 hours a day would have another positive side-effect: Companies could no longer time market-sensitive announcements to 4:10 PM. Companies tend to do this (especially in the current environment) so that investors have time to sleep on the announcement, before dumping the stock. That's simply not how the market should work.

It's time to move into the 21st Century -- into the Internet era. If millions of Internet merchants can sell products 24/7, then why can't the ASX?