I think what is hard for the naysayers to see is that bitcoin is a complex beast that has many functionalities (jack of all trades). They point out that bitcoin is useless as a "insert_use_case" since we already have this "fill in the blank", and they only see limitations.
Do we all remember when internet was only text-based you needed to use tools such as gopher or newsgroups readers? Email was not quite so pretty and easy to use 15 years ago, that's why Blackberry capitalized on a niche device that was always connected.
Bitcoin is:
a digital currency vs physical currency USD
a payment method vs credit card
a store of value vs gold
a P2P anonymous bank account that doesn't require names/addresses/SSN vs Swiss bank account
a payment settlement network (blockchain) vs payment processing network
a global P2P banking network (blockchain) vs SWIFT
a financial asset/investment vs traditional investments (stocks/bonds/real-estate)
In any single one of those categories, a critic can find faults in bitcoin and will argue it's useless.
It's easy to say Gold is a much better store of value as it's universally accepted as valuable anywhere in the world and yet, one cannot travel with a million $ worth of gold or risk being confiscated at a customs/border.
It's easy to say credit cards are much better to use as a form of payment as most online and physical stores accept it, but a person cannot use a cc to wire transfer $50,000 on a Saturday night to a family member needing an emergency operation halfway across the world for a cost of less than 50 US cents and the process take less than an hour. Truth is there's a cop out on this if you're in the US, you can have a Shift bitcoin-backed CC.
Bitcoin is an experiment in creating a financial system outside of any government controls and I hope it succeeds. I'm invested in bitcoin.