[DidYaWipe]

Good point, and surely a valid concern... one that Apple has forgotten in some places today. Look at the utterly useless icon/thumbnail view in Finder: Contents don't wrap within the window. There could be dozens or hundreds of files off-screen in limbo, and you'll never know.

There are, of course, ways to indicate "more controls this way" with an arrow or other affordance when there's a toolbar or menu overflow, though.

Anyway, the point is that by the time OS X came along, other platforms had solved the problems but Apple rejected those widely-accepted solutions.

[IIsi50MHz]

When scrollbars are not hidden, icons out of view are more discoverable. This used to be the only way Finder windows worked; there was no option to hide scrollbars. But the Apple decided scrollbars should hide by default, and be very narrow, and be low-contrast… hélas, hélas, c'est pour toujour.