The concept of what we currently call a "full node" or a "non-mining node" simply didn't exist when Bitcoin was first created. Mining became centralised much more quickly than anticipated, so the solution was to offset the power of miners with the balance of non-mining nodes. This gives ordinary users a voice without requiring them to spend a small fortune on ASICs and, most importantly, preserves decentralisation by making it so that a small number of miners wouldn't be able to act unilaterally and impose changes that users don't want.
The thought that non-mining nodes hold any power on the network is pure and utter nonsense.
They do nothing except give the manager of said non-mining node a warm fuzzy feeling that has no value in the real world.
Point , Non-mining node dumbasses such as windfury have been wanting a piece of transaction fee or btc rewards paid to them for years now,
and they get laughed at behind the scenes by the mining node operators.
All Non-Mining nodes could be turned off at noon, and no one would care.
Because Mining Nodes do all of the work and anyone could use an explorer or batch of explorers to compare against their internal ledgers.
Or they could just watch the github for changes.
The confusion is non-mining nodes give dummies like windfury some economic clout over the true miners,
nothing is further from the truth, exchanges or business that hold large sums of btc are the one with economic clout and they are the ones with voting power at the miners, by refusing to continue usage of your btc. And wheter they run a non-mining node or not is irrelevent to their economic power. It is their ownership of large quantities of btc that give them power against the miners, not the type of node they run.
Example:
Mining Node = Writer
Exchange/Business = Reader
Non-mining Node = Copiers
The Writer writes a new book, The Reader Buys the Book, The Copier makes copies of the book.
The Reader tells the Writer . if he kills his favorite character , that he won't buy his new book.
The Writer concern the Reader won't buy the book , keeps the reader's favorite character alive. (This is Economic Clout)
The Copiers, just make EXTRA UNNECESSARY COPIES of whatever books are written by the writer ,
and have no leverage of any kind against the writer or reader.
Since the Writer also puts out his own copies of the book for the readers , the copier has no power/purpose at all!