I'm also a Miele canister vacuum owner, and everywhere in my house where I vacuum is within range of a wall outlet. When I'm done, the cord retracts into the vacuum so I don't need to wind it or stow it myself. I guess, for me, that takes care of the issue to a great enough extent that I just never saw an advantage that justified the expense?
If you are ok with it, I think that's fine. Cordless to me is a huge productivity boost since I can just pick it up and vacuum whenever. I think most people see it as a huge win, but I haven't conducted a formal poll or anything.
Having a robot do everything is just another step in the convenience direction. It is great if you have expensive floors that you want to maintain on a daily or bi-daily basis.