The world doesn't need a cryptocurrency, it might need distributed ledgers technologies, but a distributed ledger technology that makes sense doesn't necessarily need a cryptocurrency in order to work like in the bitcoin the currency-blockchain system.
You could use distributed ledger technologies in order to send fiat currencies internationally for almost zero fees (like the ripple network is trying to do, again, not ripple the coin, and again, ripple is just an example, hyperledger and others are trying to do similar things), use it for applications such as smart contracts and others. Basically for all the reasons you are saying bitcoin is great, bitcoin THE CURRENCY IS not only unnecessary, but it creates more problems than it tries to solve, such as irreversibility (0 consumer protection, a chimera any currency should avoid like the plague), slow transactions, higher fees in the future, volatility, scalability, and countless others. And overall, fiat currencies work just fine, a new volatile irreversible currency is not what is useful or needed.
That why I am using the "cryptocurrencies = pets.com" analogy and that's why I am taking tulips only for the chart comparison as an example of a bubble that bursted even tho the two don't share much fundamentals wise.
You do understand that the currency is the incentive for people to update and maintain that distributed ledger right?
