It would be a great PR move and an amazing build of trust.
I don't know why Github was not open source to begin with.
Why do companies still think source code is a big deal? This is not Google Search or some advanced AI.
Microsoft bought GitHub for over seven billion dollars. You don't buy something for that kind of cash unless it has that kind of value. Saying they 'should' do something as though there is a problem is silly. Engineers here on HN are so quick to say what someone "needs to do" something... but in response to what? What problem are you identifying? A vocal minority of engineers have complained about the acquisition, meanwhile GitHub has 28 million users. Most of those users don't care that this happened.
They simply will be more competitive.
2. They want to improve their "Open Source Friendly" image and they've been taking meaningful steps towards it.
3. Why not? What's the downside of doing so?
Even if you prefer Android/GitLab, you can't deny that most of the early innovation was copied from iOS/GitHub. In fact, most open source projects (Linux, Firefox, OpenOffice, etc) take their lead from closed source competition... and for all those examples, that competition was Microsoft. That's not to say they can't eventually innovate, however much of the R&D, creation of a marketing, etc come from closed source.
The downside of Open Sourcing so is losing billions of dollars from companies who say "rather than paying $10k/mo, I'm going to just fork it for free".
Lastly, part of the value of GitHub is the network effects. If everyone's hosting it on their own, then there's no network effect.
GitHub :: iOS
CodePlex :: Windows Phone
Makes complete sense...
That is NOT what happened. Microsoft is in the process of purchasing GitHub, which likely won't happen before the end of the year. The agreed price was $7.5B in stock not cash.
I don't know if GitHub going open source is likely or even beneficial, but imagine if they chose to develop an open standard for PR/issue/comment data. The easiest way to show you are going to play fair and win via quality and trust is to make it easy for people to leave. IMHO, that's where I'd push for/encourage.