"strict realtime requirements" and Mac OS X (and most other off-the-shelf operating systems) do not mix and never have. Either these applications don't belong on the platform in the first place, or you are misunderstanding their requirements.
It doesn't matter anyway. What is it Apple has done recently to give you the impression that they place great importance on niche markets?
Realtime in this sense means an interrupt-driven thread that must respond in fixed time to prevent audio dropouts which are death in pro audio. Previously Apple has assiduously courted this market with their implementations of CoreAudio and AudioUnits and the purchase of Logic. OS X provides by far the best native support for pro audio apps of any operating system.
Lately all this seems to have fallen pretty far down on their list of priorities though.
It doesn't matter anyway. What is it Apple has done recently to give you the impression that they place great importance on niche markets?