if you lower the reward, less people will set up masternodes because of the lower profit.
less masternodes means less nodes to secure anonymous coin send/darksend process.
less masternodes means less DRK's taken away from the market; which results in a lower coin price.

of course that shouldn't mean "oh yes, raise the masternode payment ratio to %50 now". balance is important, miners should be rewarded enough to keep them mining. so I think %20 share for masternodes is fair.

long story short; try to get a few masternodes if you find them much more profitable than mining the coin. if you say you don't have money to get enough coins for masternodes, I would say that there is no easy money here for anybody. you have to stake something first to begin making profit over it.