> devs don't really understand how the customers use the product or why

At the risk of overgeneralizing, I think we do understand, but we just don't sympathize. Either because the product is trying to trik the customers into buying/subscribing (so naturally we don't like that kind of behaviour, even less when we know exactly how's that implemented), or because the product is designed "for babies": nice graphic colors here and there, videos, sweet transitions, whatever. We think that's all unncessary, and a simple HTML+CSS page would suffice for most products out there.

At least, that's what I have seen around. My team is currently building a fitness app. We are discussing tirelessly things like what engaging content we can use, the transitions between fitness exercises, how to keep them motivated to use the app... and the engineers I'm working with (I'm included) we all think that a simple bullet list of exercises and links to videos would suffice.

More often than not, the product just sucks and nothing can be done to fix that (e.g., Linkedin, Facebook, Quora) ... but obviously we won't say anything because we are here for the paycheck.