Mice are super subject tools. I love the MM, others in the stuido work with Logic MX, one of our team demanded a wired Apple Mouse, another one worked with her Wacom pad only – it is your direct, intuitive connection to the machine you work with, thus it is almost bio-kybernetic on a level most people cannot explain. As much as people can discuss keyboards (Apple vs retroclicky), mouse are much more intensive and personal. Some use the correct, non-«natural» movement, others like the iPhonish behavior. Changing the mouse would thus take some vintage Apple Guts (you know, like removing a drive or port) and we know how they have lost the urge to lead by change.
I personally love the MagicMouse, especially paired with BetterTouch, but when I forget to charge it overnight, I have two Logis and an Apple Trackpad (plus a Wacom, but that is awkward for everyday work) to work with, and changing the UserInterface-tools once in a while is good for the brain (and especially for the hand and arm, considering RSI). So the port is no big deal to me (except for the design-over-function part which is weird) and we all have to see that there is no possibility on this smooth almost seamless and contourless small device to put it anywhere but on the bottom.
I would have welcomed Qi/MagSafe, which would just feel natural with the MM.
Apart from that I think Apple should do a MM pro, which has longer battery life, more grip/contour/ergonomics, a better positioned port and additional buttons as the MX has, programmable per App. (But I think we will never see that ;-))