I don't see why this user shouldn't be frustrated, though. It is still an OS-specific limitation, since it appears that Windows will run them in a manner acceptable to the user.
It seems to be intentional though. I seem to recall Microsoft and IBM got into big trouble for anti-competitive conduct. This is the sort of thing that brings about anti-trust suits.
The frustration is targeted at Apple, because someone there likely made this decision... The support was likely already written, and expressly removed, because Apple makes Thunderbolt monitors. Not to mention that Apple is known for it's wide profit margin, so any cost/benefit analysis is less meaningful in that regard.
I'm not sure where you think said frustration should be directed.
Rather than speculating on what Apple did internally, I think the real question is whether Apple advertises DisplayPort 1.2 support, since this feature is part of the DP 1.2 spec. So far I can't find anything about this on their product pages. If that's the case it's basically users demanding features that were never put into the specs of a product.
The Mini DisplayPort Connector is a small form factor connector designed to fully support the VESA DisplayPort protocol. It is particularly useful on systems where space is at a premium, such as portable computers or to support multiple connectors on reduced height add-in cards.
I agree with some frustration, but getting upset that apples aren't oranges isn't valid.
Someone would need to write the driver for this functionality. I expect Intel is happy letting apple do the work, but so long as that is the case, Apple has no need to support every hardware and protocol under the sun. They merely have to support their stuff fully, and beyond that it is someone else's problem.
Intel wrote the driver for windows, and it works on Windows. That's also apples and oranges IMO.
Apple writes their own device drivers and they write them to the extend their software and hardware needs it and no step further.