The decision was made with pragmatism in mind. What do most programs in Rust want to do? Most of them are fine with panic on an error. Making your code robust against this, at least in Rust, makes things a
lot more cumbersome, and most programs would panic upon such an error anyway. Most programs that care about this possibility aren't using the standard library anyway. Therefore, for the standard library, the decision was made to panic on OOM, and to not block the release of Rust 1.0 on something that, at the time, wasn't itself a stable feature.
Three years later, I'm comfortable with this decision; three more years of waiting on Rust 1.0 would have killed it as a language. Many, many useful programs have been written in Rust since then.
Of course, you can disagree with this decision; I mostly want to communicate that it was not a flippant "who needs to care about that," but a careful decision made after weighing the tradeoffs. In the old days, those tradeoffs were very different.
Three years later, I'm comfortable with this decision; three more years of waiting on Rust 1.0 would have killed it as a language. Many, many useful programs have been written in Rust since then.
Of course, you can disagree with this decision; I mostly want to communicate that it was not a flippant "who needs to care about that," but a careful decision made after weighing the tradeoffs. In the old days, those tradeoffs were very different.