How involved should a developer be in their work subject

It's a question I ask myself more and more, or rather one that is being asked of me.

I work in a start up called Wahanda that works with spas, beauty salons, gyms and fitness centres, etc, etc. I don't feel completely unqualified - my wife is a massage therapist (you can see her therapist profile on the site), but at the same time, I just don't go to these havens of relaxation. I cycle to work to stay fit, I get my biannual hair cut sitting in my own kitchen (Ok, maybe three times a year...) and get regularly mocked by my wife for being too scared to join her at her pilates class.

On the other hand, my bosses (Lopo and Salim), as well as people who do copy and marketing live the life and regularly do their beauty treatments, massages, yoga, power plates, etc.

Does it matter if developers are not as intimately familiar with the 'product' as the people who write the articles or market them?
In a former life I thought the answer was a definite no. The subject of our job is the language and frameworks we use to construct the site, not the subject itself. Which is why I used to get annoyed at adverts for developers in the banking sector which said that developer experience in the banking sector is mandatory - presumably because their for loops are completely different from everybody else's code

Now I am not so sure.

Part of any programmers job is to be a code monkey - to create the code which meets the specifications required by the business (via an architect or business analyst or whoever). It's no bad thing. However, not getting involved in the subject of the application or web site you code for means that being a really good code monkey is where you have to stop. To have creative input beyond generating fully-spec'd code you have to be familiar with what drove the business to create those goals in the first place. As much as it can be frustrating, understanding some of the characteristics of the people who will use what you develop will help you to get it more right the first time.

Am I going to get a job in a bank? Nope. Am I going to hide at the back of a pilates class any time soon? Very unlikely.

I do, however, have a Wahanda gift voucher that is burning a hole in my pocket and I am thinking a massage might make a change from being hunched over my computer.