[Turing_Machine]

The common user interface/HIG idea makes less and less sense as software begins to do more and more things.

IRL, we don't expect toilets, hammers, bulldozers, shotguns, and surgical scalpels to have the same user interface features, and it would suck mightily if they did. Unfortunately, as those things get computerized we wind up getting the same crappy touch-screen menus and whatnot bolted on to them (imagine what using a hammer with a touch screen interface would be like).

I don't know the answer to how it could be brought about, but we definitely need some radically thinking in UI design. 3D libraries seem to at least provide the tools to make some new tools.

[millstone]

Those real life tools have a far simpler interface than, say, a mail client. As software becomes more complex, HIG increase in importance, because there is more to learn and HIG enables us to transfer knowledge across apps.

[Turing_Machine]

The actions you perform with a scalpel (or even a bulldozer) are far more complex than sending email, so arguing that they have a simpler interface doesn't really support your case. Quite the opposite, in fact. I would argue that they have simpler interfaces because those interfaces are actually optimized for the task, rather than being some jack-of-all-trades compromise.