Hi, I read through the thread and understand the general feeling of the design aspects that you want Balsamiq to uphold, but I just wanted to share my thoughts to see if I could convince you a bit more to have a rotate function :D!..
I love balsamiq, and my main use for it is to make mockups for game designs. I usually have everything I need from the basic tools, but sometimes I need to show differences in movement or position for certain game elements (for example, a spaceship that moves from one side to another, or blocks that stack in angular fashion), and I have to use some other software to rotate the image and bring it into balsamiq again. It would help my workflow to be able to rotate it on the spot. I mean, for example, multiples of 45 degrees would already be perfect (in case you’re wondering about the odd cases of ALL degrees).
In any case, just my 2 cents, thanks for listening.