This question already has an answer here:

Why don't we implement a Node Operator reward program (in the core) or if such implementation ever existed what would be the overall (Downside,Cause for concern, etc)

Why don't we use the Miner Fee Reward to pay the Nodes for instance? Without talking about the overall economic implication but more the technical side of things.

marked as duplicate by Jannes, Anonymous, Community Sep 18 '15 at 14:02

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.