Most of the developers I know are using Macs, with only myself and a few others preferring Linux. The Mac guys use the terminal, as it is a necessity. But they are relatively slow at it. Most of them don't even really use tab completion as much as they could, if at all. They also use the mouse very heavily, especially in their web browser, finder, and text editor.
The developers I know that prefer Linux, including myself, freaking fly on the keyboard. We hardly ever touch the mouse. We tab complete like crazy. We use a ton of keyboard shortcuts for everything. Doesn't matter if we are vim or emacs, it's keyboard keyboard keyboard.
I think the explanation is very simple. If you are a mouse using person, and you compare a Linux system to a Mac, the Mac will be more comfortable, especially with that great touchpad. If you are a keyboard person, the Mac will drive you insane and Linux will be happy land. People tend to change their software rather than change themselves, so mouse people end up on Macs.