Cinch/Phono output

from what I can tell, the apple TV unit does not have the ability to output analogue audio.

You mean other than the optical audio out?

I find that a huge oversight considering the amount of high end equipment that does not have multimedia types of input.

High end audiophiles don't use electrical analog outputs. They use optical audio so that there is no electrical noise added to the signal. So it seems the only oversite here is your level of knowledge on this topic.

Additionally since you apparently have not paid attention to the news for the last 15 years this is not a call that Apple is allowed to make since digital content is locked down with DRM restrictions that control what devices content can be played on AND how it can be transmitted. HDMI was specifically created to lock content so it can only be played on digital devices. Apple is not allowed to directly convert it and unlocked digital source.

it would absolutely make sense to be able to use the AppleTV as an airplay means to connect to the hifi system

Well other than that it cost more than twice as much as other airplay options if you just want to play music, and it has to have a TV to be used..... Yes other than this it "absolutely make sense" Also there is the minor detail that as the name imply's AppleTV was created for TV's to share video content.

not requiring the TV to be on to listen to music.

And how would you make your menu selections if you can not see the menus. The entire UI is centered around having a very simple remote that's only purpose is to let you select from the options on a screen. No screen no ablity to use the device.

If we are being correct about things, Cinch is a manufacturer which makes cables and connectors etc, of which the connectors are not limited to analogue audio, they are also used for power, RF, video as well as digital audio etc. So what you are looking for is a device with an analogue output.

Additionally:

considering the amount of high end equipment that does not have multimedia types of input.

would be more accurately stated as:

considering the amount of older high end equipment that does not have multimedia types of input.

Yes there are other manufacturers that produce set top boxes with analogue outputs to go with your equipment, but if you are looking for an Apple TV, then perhaps you should look at an 'older' model, you can still find the first generation Apple TV in places such as eBay.