Jakob Nielsen:

Decades can pass with even frequent system users barely learning one or two new things per year.

This means that enhancing the discoverability of existing features sometimes trumps the need for new features, as in the case of Office 2007:

Ensuring that people understood the old features was more important than adding new ones.

Get along with it:

You’re unlikely to be the first user interface in 30 years for which all users become sophisticated experts and learn all the features.