It wasn't a situation like that, yet. In this case, we (engineers) had a lot of trust with management because usually features were developed with lots of cust

It wasn't a situation like that, yet. In this case, we (engineers) had a lot of trust with management because usually features were developed with lots of customer involvement. (And when features weren't, they were usually MVP-style to test-market something.) So, in this case, I pointed out some limitations and immediately got back an answer that implied that the customer was aware of the limitations and was more concerned about something else. That's why I was shocked to find out no one bought it! Anyway, to further add insult to injury, the new feature added lots of complexity to the product; complexity that added development cost to further development.