I think the most important skill to expect of a non-programmer is presentation.
Startup success boils down to two problems:
1. Building the product
2. Finding customers
Be it personal powerpoint presentations, meetings, preparation of advertorial material, giving talks, or website content, the presentation of your product is really important. It is what differentiates a company solving real problems from a bunch of geeks doing some geeky stuff in a lab. It reveals the potential of your solution to real users.
To be fair you've ordered those as a developer. Non-programmer types are more likely to invert that list:
1. Finding customers
2. Building the product
Where finding the customers is something that they can be incredibly passionate about and actually affect. This is what the non-programmer worth their salt can add to a 2-3 person start-up. A skill-set aimed at focusing the pivots to those most likely to sell.
Startup success boils down to two problems:
1. Building the product
2. Finding customers
Be it personal powerpoint presentations, meetings, preparation of advertorial material, giving talks, or website content, the presentation of your product is really important. It is what differentiates a company solving real problems from a bunch of geeks doing some geeky stuff in a lab. It reveals the potential of your solution to real users.