Just to clarify, this is WontFix on Server 2008. This is in no way a statement that MS will not do this in upcoming operating systems (nor is this message a confirmation).
What I don't understand is that Microsoft provides their software in ISO form, but then doesn't provide a way to access the ISO. It always necessities installing a third-party program to either extract files from the ISO or create a virtual CD-ROM to mount the image.
Linux and MacOS both support mounting images out of the box.
Linux and Mac also have a perceived software deficit. If not to consumers, definitely to businesses. The more software is on Windows, the more people go to Windows, ... etc.
One could choose to view that forcing MS users to use 3rd party software to a common problem is actually 'supporting the ecosystem'. Someone in Microsoft could be saying that they aren't forcing users, but giving them the choice.
So what happens? The implement ISO mounting for the most part but either have compatibility bugs or they extend the functionality to benefit its own ecosystem better. People complain about that too. Think carriage returns (\n\r) and Internet Explorer. People hate Microsoft for these reasons.
So really, they piss someone off either way. So doing what costs the least amount of money (nothing) is often best.
That said, asking "How does server administration on Server 2008 and related products compare to other platforms?" answers a larger and more important question than "how do I mount ISOs on Windows?"
Doesn't Microsoft still distribute large fixes, service packs, MSDN, TechNet, and the like as downloadable .iso images? Do they seriously expect people to waste hours burning piles of physical DVDs for that sort of thing?
Sneakernet is apparently still an essential part of their network stack. Good luck if your server is mounted in some data center you don't have easy access to. Remember this next time you hear them say they're "betting the company" on cloud computing. They just don't get it.
Seems to be their filosophy that one can do almost nothing with out-of-the-box Windows. No basic tools integrated, eg. ssh client or pdf-viewer (when I last checked).