It's not about assuming that devs are only worth their coding skills, it's about recognizing that their coding skills are what they're hired for (and also what they're extremely highly paid for).
It's fine that you have a non-technical creative side, but it's frankly not what you're paid for. That's true of everyone in the organization - I'm really enjoy writing and am very good at it, but I don't believe I'm being mistreated or underutilized because I'm not asked to do copywriting. That's the purview of marketing, not product.
This is even true within engineering - if you have experience working on both iOS and Android apps, but you interview for and are hired for a role on the company's iOS app team, nobody is undervaluing you because they don't also ask you to work on their Android app.
Businesses benefit from specialization and focus of their employees. Product exists to gather requirements and define specs not because dev can't, but because that's not what developers are hired to do.
