It's hard, many of us are working for companies where there isn't a "Button UI Guy", heck I'd venture that most of us fight just to have QA people, let alone specialties. So we're forced to wear a bunch of hats and we like saying "Yes", that's how we got here in the first place. But what about when you should say "No" for the good of the company?
Dan is the CEO of Widget Co, and was meeting Raphael for drinks one night. They got to talking business as they always do, and some guy slid over and said "You're the CEO of Widget Co? What do you guys make over there?" To which Dan, with a confused look on his face, because the answer seemed obvious, said "We make widgets at Widget Co, hence the name...", and returned to his conversation with Raphael. But the stranger persisted, "You see, my wife works for you, and all she talks about is the gizmos she has to make, not widgets." Dan was clearly upset now, "Why yes, gizmos are a feature of the widgets we make at Widget Co." Now the stranger had him, "So you make gizmos at Widget Co.? That doesn't make sense." Raphael at this point made a hasty exit with a woman he met earlier and Dan just stared at the bottom of his all-too-empty glass and replied simply by sighing.
It happens everywhere in all industries. The key is where your expertise lies. It may be a natural evolution for a stainless steel company that usually ships unfinished steel to start making finished goods. But is it a reasonable extension for a law office to also offer lawn mowing services? Probably not. At Passageways, when we saw that we had a need for a search engine we knew it was outside of our expertise, we were a web-based portal company, not a search algorithm company. It was time to get outside help, and we did.
Knowing what you do, and doing it can be two separate things. The cause for disparity is often listening to customers "too much" and letting them steer you on their individual needs while losing site of the company's goals. Don't get me wrong, customers should have a voice that does not fall on deaf ears, otherwise you can kiss your revenue goodbye, but those voices need to be reconciled with the overall vision so that healthy decisions can be made, such as asking Gizmo Inc if they'd be willing to sell us some gizmos so we can get on with the widget making.