"Why is it so expensive?" - commentary from someone who does this for a living at Sequential
Small Volume - each unit is more expensive than a large volume product, you don't get price breaks on any components or tooling costs
Design focused - Who is the product for? It isn't for people who want to spend 250$ on a Behringer mixer. It is for people who want something that is high quality and doesn't break. Reliable. For people that rely on their tools to be creative or appreciate design. You are paying a premium. See Apple for lots of examples. This is also one of the biggest strengths of the company, if you want something cheap you're looking in the wrong place.
Complex - the amount of balance of various components here adds a lot to the design and development costs. Battery is an unusual feature but puts it in a different product category. Balancing that with the audio quality and reliability is not a trivial problem. Add in wireless, audio drivers (not trivial at ALL), Complexity increases development time and adds risk to the long term stability of the product, that is added into the cost.
Most of the small features feel like somebody there thought it would be fun and/or easy to put in. It's a good way to iterate through design ideas, you have to see it in reality. That type of prototyping isn't easy. Most people don't use 90% of the features but when you are in a creative industry the 1% that does absolutely LOVES it and uses it in ways you never expected. It's difficult to balance the amount of development you put into fun things vs. business cases.
If you are trying to figure out why you'd pay for this you aren't their target market. It's far more interesting (to me) to think about why some people WOULD pay for this and what a market looks like that you are not a part of