I hardly use the scrollbar either (even when using a mouse), but the scrollbar is an important visual clue what portion of a scrollable page is currently being shown, no matter what the input method is. Apple could just have turned the interactive scrollbar into a much slimmer non-interactive hint and all would be fine, but no, they had to go "form over function" again :/
I see your point, but I still think this is a matter of preference and priorities.
I stand by the original argument that for most people, a minor twitch of their fingers on the trackpad reveals this information if they want it. I very rarely do want this though, and on average I prefer that it's not shown by default, or until I move.
This discussion was prompted by a UI fail in presenting relevant security information. Relying on permanent scroll bars would still be a UX fail, even if it were the default on Macs.
