Earlier quoted context omitted.
> Like Maxwell's equations? Maxwell's equations don't yield workable GPS. You need general relativity. Similarly, you need a blockchain (or some similar solution for the double-spend problem) for a workable digital currency. > Anyway, for (b) security it claims to be secure by providing a way for the bank A to reveal the identity P of the double-spender mathematically from the duplicate spent coins. Yes, exactly, it…
Well, whether or not you agree, there is some newness. The Okamoto-Ohta scheme might seem like handing out gift card codes to people as payment to you, but there are interesting mathematical properties to it that move responsibility further up the ladder than simply saying you're SOL if you've been handed a spent card number. If you hold BTC you might not want to hear that Bitcoin has faults, but it does. Outside of…
That's the thing, with decentralized digital currencies, there is no "further up the ladder", nor can there be, so this property isn't appreciated. And decentralized digital currencies are the only ones that are finding any traction.
> Outside of practical problems, it's labeled as a cryptocurrency but the design of it, besides wallet keys, uses little cryptography.
You should read up on the latest developments. Bitcoin is essentially a platform now that has hundreds of different technical innovations (most of them involving cryptography, which you seem fond of) built either on top of or with modifications to. Everything from segwit to Lightning Network to n-of-m escrow transactions to Darksend to sidechains to blind transactions to Ethereum to Namecoin etc. etc. etc. You could spend months reading up on all of this. It's all made possible thanks to Bitcoin. Also, did you know that Bitcoin has a built-in scripting language (from the very beginning) that allows all sorts of nifty transactions that are way more complicated than "Send N BTC from A to B"? You should look into it.
> the block chain itself is completely centralized, while the miners are decentralized.
Huh? Every full node has its own copy of the blockchain. It's way more decentralized than mining, which is limited to a smallish number of pools. That everyone has the same copy of Bitcoin just means that everyone is living in the same objective reality; it has to be the same, otherwise you could never agree on anything. Absent a currency that has intrinsic value such as gold (and there are big problems inherent in that too), and which is impossible for virtual currencies, the value comes from everyone agreeing on where the value is.
> Waiting 10 minutes for a charge to pass before getting something out of a vending machine
Well realistically a vending machine would just do a 0-conf transaction, because pulling off a double spend would be way more effort than it's worth just to steal a soda. But also, you do realize that ten minutes is just a tuning parameter, right? There's no fundamental reason it has to be that value. There are altcoins with faster blocks, and Lightning Network does side-chain transactions that confirm near instantly. It's not an intractable problem, in other words; you just tune some parameters or use something built on top of Bitcoin. People are much more willing to use modifications on top of Bitcoin to solve these problems than they are to give up on the decentralized nature of it entirely and just go with something else. It's no accident that decentralization is the killer feature, and anything lacking it is a non-starter.
There are plenty of centralized financial payment services that are good enough. That ideas in that article you linked to never caught on because they don't add value of the kind that people care about. It's no accident that it was never actually implemented. Bitcoin, meanwhile, just did that one thing, decentralization, but because of that it has been used by millions of people worldwide, and is sitting at a total market cap right now of ~$7 billion. You can't really argue with results. You can keep arguing until you're blue in the face that decentralization doesn't really matter, that all these other things are actually more important, but that's not borne out by results.
> or having your card information stolen by a faulty vending machine card reader for your run-of-the-mill credit card.
This is an unrelated issue related to push vs pull transactions (push is better). Credit cards are pull transactions. Bitcoin is push. Chip and PIN as implemented by credit cards in most of the rest of the world are also push transactions, and also handily solve the problem.
> The truth is both BTC and other digital cash forms have the same problem - there are no chargebacks. So if you purchase something at a distance with either, there's no way for a refund if someone runs off with your money.
Yes, sending Bitcoin using a raw transaction is like sending cash or a money order. No argument there. People are used to those risks however. Also, using the aforementioned Bitcoin Script language, you can write multisig escrow transactions that do allow what are effectively chargebacks. I suggest you look into it. You are arguing many things as being faults of Bitcoin and the related ecosystem which do in fact have solutions.
I've been fairly heavily involved in Bitcoin for about five years now and this is just scratching the surface. I do recommend learning more -- most of your concerns are already addressed in ways that do not compromise decentralization.