The majority of crypto currencies that make use of masternodes, split their block reward per block equally between the mining and masternode distribution mechanisms. The intended fairness of this reward distribution can be subverted by the growth of masternodes held by large investors without limits leading to potential centralization of the budgeting system much like having a majority shareholder in a company. The additional benefits of masternodes can lead to less number of users conducting Proof of Stake (PoS) mining activities and thus lowering the security of the PoS network.
Masternodes do provide a valuable service and should be rewarded for that service, but our aim here is not to reward them way beyond the extra value they provide. For we believe that doing so disproportionately benefits masternode owners above and beyond other users of the system and ultimately leads to a greater degree of centralization.