I think the pressure to keep adding new features on a yearly basis is more likely to please the investors/shareholders rather than the users. As an user, I know what I expected to get when I purchase the device, and just want it continue provide the same functionality. Occasionally adding new features without impacting existing functionality is nice, but I’m completely happy with the device just keep doing what it does.
On the other hand, the investors/shareholders are the ones who would expect the company to regularly come up with new products, new features, with the hope of driving business growth. With Apple’s stellar track record of growth (especially under Tim Cook), the pressure will only get more severe.