"Those that are claiming [governance is] not necessary for e.g., blockchain are IMHO wrong"
Depends on exactly what you mean by governance. If you define governance as "Protection of the system from non-technical threats" then I think you'll find few willing to argue that all legitimate non-technical threats should be protected against, whether you call it governance or not.
I do find it interesting, however, that your example of why we need governance, Ethereum and the DAO, is an example of a technical threat (software bugs, and exploitation thereof) which probably needed less governance, not more, as the resolution was essentially the worst possible case scenario in consensus technologies: a permanent fork. Had they done nothing governance-y at all, the investors would have lost most of their money on a risky investment, which would have been exactly what they signed up for and agreed to when they signed the transactions that bought in, and all would've been well.
A better example, IMHO, of the need of governance in blockchain is Bitcoin. They have some serious need of solving of non-technical problems right now, haha
Of course, in a high level discussion about humans, as it is with governance, it's hard to be precise about where the governance stops and where the tech starts. The way I try and do that is with the Principle outlined above - we automate what we can, then we govern the rest. E.g., good example of this is Bitcoin - the automation design solved the problem of double spending protection, so we no longer needed that central party to do that. But there was still "all the rest" to deal with. That's the domain of governance.
Then, of course, we can always accept a risk - as you describe it's entirely possible to say "code is law" and when the code hands it all over to an attacker, then the result is clear, you lost. But, saying it up front and expecting it to happen depends on humans behaving like computers. Humans aren't deterministic, they can happily say one thing and mean another... And so it happened. In terms of this article, Ethereum had a near-null governance layer at the start and then invented one on the fly when suddenly needed to satisfy the bulk of the "money". So, one can say the code was fine, leave it, but if people don't agree, then change happens. That's governance, and I'd argue it's bad governance and badly designed governance. We can do better.