One is that the paradox of bitcoin adoption is that it can't take off without a normal banking system. And if you had a decent banking system, you wouldn't need bitcoin in the first place.
That is, fraud is a big issue in online retail. You buy product X online and then you 'charge back' your transaction and end up with a free product. Merchants then have to solve this by starting legal cases and provide evidence that a product was supplied blablabla. Sometimes this costs more than it's worth. Bitcoin faces a lot of these problems, too. How do you acquire bitcoin? You can't through Paypal because of this fraud, everyone charges it back and Paypal mostly ignores evidence that bitcoin was indeed supplied. As a seller you can't really make a case and win.
So you end up with these big companies that act a bit like banks. They require you to verify your identity, your residence, bank account etc. All to prevent fraud. And of course all of that has costs, so they charge you 1%. And then you pay them not through a credit card, that's 2.5% in fees which doesn't work if you pay $100 to get $100 of bitcoin. So you pay through ACH, which takes a few days but is cheap.
So you end up with a service that sells you bitcoin for 1% that takes a few days. Why? Because there's no way to safely send money cheaply and instantly without fraud, which is what bitcoin allows you to do and solves.
So the paradox is, if everyone had bitcoin, it wouldn't be a problem. But they don't, so we need banks. But if banks worked well, we wouldn't need bitcoin.
Over time this becomes less of an issue of course. This is what made Coinbase big, not its storage, but its exchange function for US customers. As a wallet, it's not the biggest, Blockchain.info which does not see your private keys (it's a software layer) has almost a million more wallets. So it's big for its exchange function which has little to do with centralized or decentralized storage of money.
The second part is centralized storage. This is a function of culture and software sophistication. In the early days most bitcoin software wasn't user friendly and not very well written. Today we're seeing changes. In fact, Coinbase has a multi-sig product, which is a software solution allowing you full autonomy over your money, and Coinbase none. That's not centralized storage, users retain full control over their private keys and Coinbase offers the software to facilitate it, much like how an Excel sheet facilitates your personal data analysis but doesn't award Microsoft ownership of your data. Over time we'll see products like this emerge more and more and people will have a choice to move away from centralized storage, and culture may shift towards that, too.
In short though, bitcoin wasn't about 'never use a centralized company'. It's about a protocol layer that's not proprietary, with a currency that can't be forged or printed to fuel political agendas (like militaristic foreign policy). The fact that centralized and decentralized solutions become available on top of that layer is both fine. Much like how a decentralized internet would be awesome despite the fact it would still see centralized repositories of data like Facebook, it's not about which services become most popular as long as the underlying network remains free and open.