Why do something one way, when you can do it three ways? Seriously though, I imagine it had to do with making the UI more like Photoshop's.
Does seem pointless and confusing though.
WOW... i never thought of it that way... everything would be so much better if there were only MORE ways to do it!
haha... u r funny.
When you draw a vector shape, the properties panel shows all the options of editing it, including the gradient effect (as an option), but with paint bucket tool is not the same.
A designer that wants to create or edit a gradient effect on a bitmap, needs to use paint bucket tool and that is when it is not clear enough seeing the paint bucket tool and needs to see a gradient tool icon .
I think that could be the only serious reason for the gradient tool existance, even though in FW gradient tool is a "sub tool", and you can only see the tiny black arrow on paint bucket tool.