Making this game into a full 3d game would probably require a significant amount of work. I can say from my own experience of developing mods for Morrowind in the TES construction kit that making multi level structures was a real difficulty tedious and time consuming task. and that was only placing and aligning objects, nowhere near as complex as the interactions we have in Dwarf Fortress now.
I can't see any reasonable and easy scheme that would allow us the same full featured and complex control we have now.
How would you manage the multiple layers?
How would you easily show the different depths of each area at any camera angle?
How would you allow people to select areas for digging/channeling?
How would you indicate the numerous types of rocks in Dwarf Fortress and still maintain a reasonable download size for the game?
These and many more questions would have to be answered before Toady could consider the development of a 3D dwarf fortress. Many of these interface requirements have no real precedent in modern game design which meant Toady would have to work on not only features for Dwarf Fortress but a sane and clear interface that can present the overwhelming amounts of information in Dwarf Fortress to the user. Our current text interface struggles as well, how would you expect the 3d version to do it without becoming even more visually cluttered?
I feel like you haven't given much thought to any of these considerations, it's unfair of you to make demands on somebody who doesn't ask for any money for his game, only that you donate if you want too. Donation here implying to me that the money is given without demands or strings attached. Had you been less agressive in your original post you might not have come off as so self entitled.