We could "force" voting by making people pay a tax for not voting when they are eligible (people with nonzero importance and at elast 10,000 NEM are eligible).
Not sure if that would do more harm than good.
It's a difficult problem, which exists in every free and democratic society.
It would give a real monetary value for participating in voting that would benefit voters and punish non-voters through indirect inflation. People who harvest the blocks with these special assets may not be as thrilled as with real NEM, but I do not think there will be so many votes as to make a practical difference in the economy :) Also, because the tokens are fungible for transaction fees, they have a functional value and could be easily converted into real NEM (or used to pay transaction fees even).