Elaborate on what? It seems rather obvious that a popular game with a minor bug rendering it unplayable would have that bug fixed by someone for free if it was open source.
Or do you want me to elaborate on why it's too bad? Well, pinball is the best game that was ever included with Windows, so it's unfortunate that it's not still there.
First, it was not a minor bug, it is a major bug that made the whole product unusable.
Second, the whole code base was one big, nasty, uncommented mud-ball. From the article: "... we simply couldn't figure out why the collision detector was not working. Heck, we couldn't even find the collision detector!"
I was genuinely curious to hear how you think sprinkling fairy dust open source on top of the mess is going to magically fix the issue. I am not talking about reimplementing the whole thing from scratch (which nobody is prohibiting you by the way). I am asking about the value added to the community to fix this particular piece of crap.
But, based on your response, I am going to risk even more karma and chalk it up to trolling. You did not address my question, and don't even look like having read the article or understood the issue. So... have fun!
People not in the middle of working on the program don't understand the magnitude of the problem and it's way easier to be an internet warrior shooting off their mouth. GP's comments made it appear to be trolling.
In fact the problem was way worse, the program used floating point for movement computation and could accumulate floating point errors along the way and moved too much. The floating point size was changed in 64-bit and exacerbate the problem. That's probably why the collision detection didn't work.
It's better to rewrite from ground up than fix it.
Windows has millions of users. If Microsoft went out and said: "Hey, this game you all like has a bug in 64-bit versions, here's the source, any ideas?", I bet tons of people would have invested a couple of days. As you see in the blog post, it was not even possible to invest that amount of time into the problem within Microsoft.
Open source is not magic in the least. It just enables other people to try and help out if your project means anything to them.
If the game had been open source from the beggining, it probably would not be an undocumented mess right now. Sure, open source is no guarentee for quality, but open source and popular means that many eyes will look at the code, and it will naturally develop documentation.
Why are you so angry? Is it so offensive to you that I think that millions of programmers throughout the world with nearly unlimited time could do something that a couple Microsoft programmers couldn't do in a short period of time?