A masternode can support the network with a nodelist, mixing, supply quick download of the blockchain. DASH allows you to vote for improvements. Depends on the masternode.
I would setup one for ESP, no care of a possible income.

Coins with masternode prove that people have still interrest in the coin. An important point which makes masternode coins often more valuable than others. A masternode owner proves
that he is taking care of a part of the network with bandwith / electricity / hardware / updates / his time. Holding and not willing to dump the coin = value.

Best example is DASH, for DASH you need 1000 coins = 83.000 US$. With this, a masternode owner proves he is seeing a good future not worth selling it right now for 83.000 US$. Thats a coin you can trust
at that moment. Remember, fiat money is nothing else, just a peace of tamper proof paper with a promise of value on it.