The problem is that the word "may" covers a wide range of probabilities. Yes, there is a small but non-zero chance of adverse reactions to the vaccine. But it's orders of magnitude less dangerous than contracting one of the diseases it prevents.
This. Also, a year ago Apple was still selling some models of the 4th gen iPod Touches, which are the equivalent of a three year old iPhone 4 but with half the ram.
I've been forced to do this by a publisher and did not feel good about it at all. To be fair, though, it was a quick port of a flash game that was completely unplayable on the 3gs and not fun on the 4.
A quick search will bring up tables of which device requirements will disallow which devices, so it's not an unheard of practice. But nobody is excluding potential customers out of spite, it's because the older harware genuinely can't handle the apps.
Most IDEs let you set a hotkey to run the current file through an external program (I generally use Ctrl-Shift-V to open in Vim) as well as a setting to automatically detect and reload a file that's been changed outside the IDE. It's not perfect integration, but it works pretty well once you're used to the workflow.