A simple way of securing your funds by means of a saving account which cannot be easily drained.
Yeah, this is important. Although if a blockchain is smartcontract-capable, it isn't necessary to build it on the blockchain because any wallet can add it as a smartcontract. But even then it might make sense to put a simple savings account as a core feature to make sure that it's easy to use and implement in any smartcontract/application.
A way to recover your account after being hacked.
This is also an important feature, especially when mainstream markets are getting closer.
A GUI which offers UX on par with legacy systems.
This is not exactly a blockchain feature but build on top of the blockchain. While very important for mainstream markets, it's not something that blockchain developers need necessarily to focus on. Blockchain technology should be kept separate from everything else so it won't become too dependent on one particular UI. If the blockchain is designed properly, there will be demand for UIs and other developers will be willing to make them.
And we are missing one more crucial thing: every blockchain needs a constitution. Or in other words, a list of principles which are not able to be enforced by the code itself, so they need to be safeguarded by the community.
Those are the meta-rules (which are usually implicit) yet when they are made explicit (before anything controversial happens) they can prevent a lot of drama and prevent a deadly fork.
Yeah, something like a constitution is a good idea. That belongs to the other side of the coin. There is technological side, which I'm describing here, and then there is human/organizational side, to which a constitution belongs.
I disagree a bit, as I remember from the time when BTS 2.0 was coming into existence that blockchain data needs to be properly exposed in the form of a robust and comprehensive API - otherwise creating a responsive GUI is much harder or even impossible. I remember Dan talking about it at that time and him even coding a bit in JavaScript in order to better understand the front-end perspective.
Good point about the API. It's so important that it might be reasonable to add it to the list.