And yeah, that cancer line was meant to snarky and cute, not factual. It does not really matter more than me indicating the obvious, that this is a big culture shift if you look at the timeline. I think MS has ways to go too, and the long game is where we will see how it fares, but I want to make sure we encourage the good. Or it will languish, as "no one cared after a while."
If you look at any of the projects that are on GitHub now, the public issues list is the issues list. You can see all the dev comments, scheduling via labels, pull requests, code reviews, etc.
https://github.com/aspnet/mvc/issues?q=is%3Aissue+is%3Aclose...
https://github.com/dotnet/coreclr/issues?q=is%3Aissue+is%3Ac...
For products that aren't on GitHub, public issue lists like UserVoice have still been a big improvement (in my opinion) because they usually keep the bugs / issues / feedback around until it's fixed, and the votes accumulate so the important issues keep bubbling up.
A lot of products have UserVoice set up, a lot of dev product teams (dotnet, asp.net, etc.) are looking for GitHub issues.
For Windows 10 I'd recommend using the Windows 10 Feedback Hub - if you hate something about Windows 10, post feedback in the Feedback Hub before you uninstall it.
Visual Studio has this page that explains where best to submit feedback / bugs / feature requests: https://msdn.microsoft.com/en-us/library/b8akas30.aspx
There are lots of us who see your comments on HN / Reddit / Slashdot / etc. but having been part of the Microsoft ecosystem (both inside and out of Microsoft) for many years, I can tell you that there's a huge difference between "I've seen some unhappy comments about X" and "Our feedback numbers show 68% of users want us to improve feature X". Also, specifics are important - a detailed issue report with repro steps and recommendations for what you'd like to see work a whole lot better than "@drunkvs LOL VS suxxxx ikr!!!"
Also, just because I'm an ocd fact checker, Ballmer technically didn't say "open source is a cancer". He said that Linux is a cancer, referring to the strong copyleft license requirements (https://web.archive.org/web/20011211130654/http://www.suntim...). [yes, I very well know that you can run software on Linux without that software being GPL. I'm writing this from Red Hat DevNation :)]
Regardless, I can tell you that our current CEO and everyone I work with is excited about writing great software that runs everywhere.