If you buy and sell cryptos, you almost certainly have a Coinbase account. If you're getting into cryptos, Coinbase is almost certainly where you start.
So, the fact that Coinbase is adding new security features is indeed good news for everyone in the cryptosphere.
I think the vault on Coinbase is a great option, although it does take away one of the best features of cryptocurrencies. Lots of people say "If you don't own the private keys, you really don't own the coins." While that is a bit of an exaggeration, it is mostly true. When you hold your cryptos with any third party, there is always risk of them getting lost, stolen, or hacked. Mt. Gox is the biggest and best example of this happening. Many people are still waiting to see if they will get any portion of their cryptos back.
The only problem for a lot of people coming from regular currencies is that they are so used to the banking system, that they expect a third party to hold their money. In many ways, holding your dollars at a bank also contains similar risks.
I think the vault is a decent option for people just starting to get into cryptos. There is a lot to learn on various wallets and security measures, and plenty of people have lost coins managing them on their own. That is the flip side of being in total control of your money- you are totally responsible as well. No bank can reverse a transaction, no FDIC or insurance company can reimburse you for a careless loss, there is no one to appeal to.
Ultimately, I think everyone should end up managing their own. But keeping some in Coinbase vault (much like keeping some money in the bank) could be the more responsible choice for some.