Microsoft sent out a high level research team to a company I worked at to collect data and feed back on Outlook. During my interview I asked the lead researcher why he's going through all this trouble to collect data, when he uses the same product himself, and can pay attention to how he's using it and see the disconnects between the use cases and the UI directly? It was a fair question, but I don't recall him having a good answer, other than jotting a note and agreeing. My follow up question was surly there's innovation in Microsoft around UIs, why not interview those folks? To which he and his team laughed and said you don't want any of those folks ideas. Amusingly honest, which I didn't expect.