In any given block you can see 3 eth is rewarded to the miner who found it, and 0.??? is rewarded for process transactions. Both operations require computation and storage power, but clearly finding the nounce uses 97% of the resource and process transaction use only 3% at max (gas limit * block utilization) / (3 + gas limit * block utilization) How is dapp decentralized if one ends up host their dapp on AWS or Azure.
In any given block you can see 3 eth is rewarded to the miner who found it,
The miner who finds the PoW is rewarded the block reward (3 ETH) and any transaction fees (and uncle rewards).
and 0.??? is rewarded for process transactions.
I'm assuming by this you mean the other miners and full nodes in the network (i.e. those who weren't successful in mining the block). If they want to run a full node, and/or continue to mine future blocks, they must verify that all transactions in the network equate to valid state changes. If they don't do this validation step, then they have no way of knowing that their node has a reliable, correct state. Any miner who can't guarantee this baseline state is going to be wasting their time (and money) mining potentially invalid subsequent blocks.
So yes, all nodes will run the transactions, but only the miner who mines the block will get paid for it.
How is dapp decentralized if one ends up host their dapp on AWS or Azure.
This is a different question. By Dapp, do you mean the front end or the back end?
The blockchain is the backend, so as long as the AWS or Azure instance that hosts your node is connecting to the main network, then it's decentralised. If it's not connected to the main network, then it's not much use for anything. (Unless you're planning to run a private network.)
If you're talking about the front end, then yes, these would usually be hosted on a centralised server. The alternative would be to use something like IPFS or Swarm.