What is to stop the NSA, FBI, any central government or bad actors buying up loads of Masternodes?Have you not thought about bad actors and if we let everyone vote they can easily vote to hurt the network??
The reason to have the barrier of entry so high to vote is it will ensure the people who vote are doing so to benefit the network, not hurt it. If they vote to hurt the network they stand to lose their own investment. Think of the MN owners as board members of the network, not every man and his dog who thinks they have a say when they dont put their money where their mouth is.
The fact that Masternode owners control the direction of the Dash project weakens the decentralization aspect of the currency in my opinion.