There is a natural trade-off in Application design between the effectiveness of new users, who are unfamiliar with an application—and the effectiveness of power users, who are already familiar with an application. New users need tutorials, discoverability, and deeply categorized menus. Power users need more items on screen at once for quicker access, and for more features to be packed into those items. More items on screen means less space to Telegraph [] the capabilities of controls. Note Photoshop's icons, or Premier Pro's multi-use timeline.
As long as features don't consume Scarce Resources[[TODO]] the trade-off can be mitigated. As in the case of keyboard shortcuts, which won't harm new users experience.
Many applications have an intended user base—either new comers or power users—but any design must still account for new users. This is often the intent behind Tour-Guides, which show up on first entry and never again.
Software intended for Power Users has less room to Telegraph[] the utility of controls. For this reason, most actions should be Reversible[[TODO]], and provide copious Feedback[].