I can understand where some people would like to have a "Line Tool" to make things easier when drawing simple lines. My only concern is that, should this idea be taken into consideration, the old ruler and stencils will be taken out and that is deffinately something I don't want to see happen. A line tool is good for making simple straight lines quickly, but has no real "edge" like the current ruler has. There would be no way to mask an edge when using tools like the airbrush (this is where the ruler is better then say a square stencil, because one can easily extend it's range without increasing it's scale).
The things I'd really like to see changed (or more to the point, "added") is the abillity to set the ruler and stencils oppacity and the option to lock them in place so when one uses the "Alt"+click color picker shortcut to grab a color in the picture it doesn't think you're trying to scale the stencil instead.
Nothing is easy to the unwilling.