So instead of giving a % of the block reward to the nodes,
While that would be a good idea, that is unfortunately the way Bitcoin currently operates. Working now, and ofr the foreseeable future. There seems to be no fatal flaw in this.
if you start paying nodes.
this will cause a fee hike to try to 'incentivise' nodes while keeping the miners mining
all that will happen is 10 people running 1000 nodes each to get 1000x the income of just running one node.
this will cause node centralization (pooling nodes/node farms/sybil attack)
this will dilute how much each node receives because the share needs to be split by 10k nodes.
this will cause ethical node users(1node/head) not receiving much/anything
snowball effect causing the opposite of the hope