Two reasons:
1. There's no GOOD reason for this change to happen. It's change for change's sake. Sure it's more logical, but standards of time or measurement aren't changed for just that reason, they get changed when they're shown to be BROKEN and while our current time system is less than optimal, it's far from broken. Blame the Babylonians.<p>2. Establishment.<p>Dethroning a company, which has marketing, and products, and such is one thing. But to dethrone a concept requires a great big change, cataclysmic in some ways. Ignoring the first point, Internet time could have succeeded if it only reached critical mass.<p>Imagine if Twitter decided that starting today they only showed message times in Internet time. Would that be enough for people to quit twitter? Possibly. But would they lose that many people? It's really more about the here and now, so people shrug, call it eccentricity, and the geeks go about educating people trying to make them understand the merits of the new time system.<p>If it and Twitter hung on, more and more people would come to understand it. This is the first hurdle now behind us.<p>Many of us Americans understand the metric system, but the government still uses miles, feet, lbs, gallons, etc. So the people then have to begin calling for the social change, and dealing with those who didn't want the change. This is the second major hurdle. Even if a loud and vocal group advocated the change, it would require a great deal of reason to enact the change.<p>Consider all the clocks that would need replacing. The epic sweeping changes to the clock and watch industry. They would fight tooth and nail to avoid such change. The costs would be astronomical. Sure they'd see a surge in sales from those who adopted the new system, but I doubt they would see much profit after the change to marketing, production, etc.