Moving your thumb or index finger around across a 2.5" x 1.5" rectangle is, to me, more ergonomic than repetive motion of a mouse.

It certainly is, I couldn't use a regular mouse anymore.

Plus the one I have (built into these now-discontinued keyboards) allows me to click mouse buttons and scroll horizontally and vertically using certain areas of the touchpad.

Should you ever need to replace your touchpad, have a look at one of these. One finger moves the text cursor, two the mouse cursor, three doubleclick/drag, four fingers scroll. There are gestures for cut/copy/paste, undo/redo, web browsing, file operations, alt-f4, emacs, ... the newest software release even allows you to redefine the behavior of these gestures.