I would love to hear why the github team waited so long to bring this feature into existence? I am sure there is a good reason (or maybe not) but it would be awesome if a member of the team would stop by and post the details.
I imagine the conversation internally went something like, "Man, attaching an image to an issue is really annoying. Let's make it not suck." An issue and pull request followed, internally shipped it to test it, and today rolled it out to you all.
That's literally how 99.99% of features happen on GitHub. :)
This is good enough for me :)