I think most people have a reasonable expectation that when you release apis, you are setting up a long term relationship with developers and not to be ended on

I think most people have a reasonable expectation that when you release apis, you are setting up a long term relationship with developers and not to be ended on a whim. These people risked time and money to develop on your platform, and usually only did so because they expected more than a few years worth of profit. Now of course there is no legal obligation for a company not to screw over the developers they attract. But it is scummy, and your reputation will be tarnished. It is not the norm yet. If everyone starts releasing APIs and screwing developers as soon as it is convenient for them, then attracting developers to future platforms will become more difficult in the future. As it stands now, you'd have to be an idiot to trust Twitter again.