Proof of work may not be the best algorithm to secure a blockchain-based system. There are aspects of PoW that leave a lot to be desired. However, PoW is a good way to distribute a digital currency. Perhaps PoW will be replaced in the future by something different, but at this time we cannot say for certain what it will be.
Proof of Work is really inefficient; it wastes a lot of electricity and computing power. However, it is inefficient by design. We do want competition between miners because that is precisely what makes the blockchain ledger secure. Miners keep other miners honest because they are all competing for the same block reward. We believe that PoW is the best way to distribute a cryptocurrency, initially. Perhaps after bitcoins are fully, or almost fully, distributed, it will make sense to switch to another algorithm to secure the blockchain.
