You don't want to know what time the sun's highest in the sky in various places around the world, though - you want to know what time people are likely to get to work, when people will be heading off for lunch, and when they'll be back. And that isn't as simple as knowing when it's 9am or 12 noon everywhere, because cultural assumptions about working hours and lunch hours are as variable as the alignment of timezones to actual astronomical noon. What you actually need is to keep an eye on people's Skype presence indicators.

12:00 is almost never midday. Even in equator, "midday" drifts by several minutes as the year goes by. Sunrise and sunset times vary a lot by latitude, so 5:00 in one location might mean sunrise, where in another location the sun won't come up for a couple of hours. Ditto for sunset. Even DST can't compensate if the sun is rising at 6:00 and setting at 22:00.

Midday doesn't have to be that precise, and you centre your day around it rather than move the day around sunrise and sunset. It may be that Swatch Internet Time was rather _before_ its time rather than something that will never catch on, but the current system works really well for pretty much everyone.