I think some peope feel the need to actually register their feelings.
Not showing up could be from a variety of causes...but to actually go and vote NONE OF THEM, which would have to be counted and published, is another matter.
We have wanted to do that in the U.K.

At the moment we only have the choice of not voting, or spoiling the paper (by voting for all of them).
This does not give a clear picture of how angry many people are with the choices.

If we ever are FORCED to vote (on threat of a fine if we do not....as I believe is the case in Australia????) then this futher option of NONE will definitely be needed.