I love stereo audio. It's brilliant.

It means I can separate out two people in an interview and adjust their levels independently or isolated individual bits without getting the other person's mouth soundy stuff in there.

Right, that's that out of the way.

Other than that - what's the point?
I genuinely can't think of any time I've been listening to music and thought "Wow, this sounds so much better."

In some games stereo separation provides some context cues for things but even then I can't say it's a feature I've found of particular use.

However I rather like surround sound!

It's only in the last year or so that I've put the effort in to get audio cables and settings sorted to get actual 5.1 out of most of my hardware and even then it's been a bit finicky (mostly due to the rather knackered receiver I'm using). With 5.1 surround (or similar) I can hear the difference though which is why I bother.

Left and right audio channels are too close to make all that much difference but when I can have an action scene surrounding me then the effect really works. It's how I found out that my parents' receiver has a maximum volume of "89".

Yep, no idea.

However hearing the war rig's horn always gives me chills and this is made all the better by being surrounded by a swirling melee of sound.

That's pretty much it. Mono is fine, stereo is sometimes useful, surround sound is fun.