Curious question of a non-native speaker: What does this phrase mean? (in general, and in this context)
+1 : My feelings after going thru basics of ethereum.
If they were to be as safe as possible, there would be less news, and they would push the traversal of those dialectics further into the history, when more people are using Ethereum and these kinds of events can do more damage.
It's beta. Don't worry about it. Come back in 10 years when the Heroku of Ethereum is released. Buy a couple Ethers now so you'll be rich then.
The problem is that it's just not easy to get all those details right from day 1, and interest in Ethereum has grown way faster than its capacity to produce a reliable, mature set of tools around it.
This is different from the kinds of objects that you would instantiate in a language like Java, where best practices suggest defining as immutable unless you have a good reason not to.
For starters, not all functions on the contract are supposed to be mutating. Marking those that are as such would catch accidental mistakes when unnecessary mutations happen.
Then there's the issue with structs, collections etc all also being mutable by default, which is separate of contracts.
Finally, none of this actually requires any mutability at all. A contract could treated as a pure function that takes initial state as input, and returns the new state as output. Such a function can be written without any mutations at all, by constructing the new state piece by piece from the old one.
Sure, it would be a more verbose (although functional languages usually offer shortcuts like "give me a copy of this object, but with these fields set to different values", making it not so verbose after all). But on the other hand, it means that you have to explicitly consider the effect of every operation of the contract on every bit of state. "Don't repeat yourself" is not always a good thing - when it comes to security, you often do actually want to make people do redundant things, e.g.: http://www.atlasobscura.com/articles/pointing-and-calling-ja....
Solidity is ostensibly designed to let people write smart contracts for Ethereum.
More realistically, it is a marketing tool for enabling and onboarding people onto the Ethereum platform, which Ethereum benefits monetarily (enormously so) from. Security and design are secondary goals to the extent that they help prevent disasters which hurt adoption or churn developers away.
Through this lens it's not a mystery why the language is "hacky". Perhaps being a good language is not even the driving goal.