This moves C# to a more modern systematic understanding of what this keyword is for, but it'll remain very rare in C# the same way it's rare in Rust, and presumably in Swift.

The choice of keyword "unsafe" is partly psychological. Turns out if you called this exact same feature "trusted" or whatever the programmers don't have the appropriate feelings about it. They want to write trusted code, they don't want to write unsafe code, so making them write the keyword "unsafe" provides that psychological disincentive.

There are standard library APIs that let you do memory-unsafe things without the unsafe keyword (CollectionsMarshal, MemoryMarshal). They're useful, but the burden is on the caller to uphold the invariants. This proposal seems aimed at making that kind of contract more explicit and obvious.

Many of us use it in scenarios where others would write a blog post about a rewrite in Rust, C++ or whatever.

CLR was designed to support languages like C++, yet many don't learn the knobs.

In a game development context, especially where C++ interop is involved and a lot of code lives across a boundary where memory is owned by C++ but you want to avoid/minimize marshaling overhead or just generally maximize performance, the unsafe keyword is quite handy, but outside of those you can indeed probably get around by approximately never using it.

There's a lot of power C# gives you if carefully curated, making a lot of cases where people previously might have seen C++ as the only option as suddenly quite viable.

... See also the somewhat arcane Unsafe.As etc APIs

Around here C# is only really used at stagnant middle sized companies with horrible code bases. The sort where the company follow Uncle Bob religiously, while completely misunderstanding everything Uncle Bob ever said. Doesn't mean the language (and it's runtime) can't be good.

C# is like Rust in the sense that a regular (web, desktop, etc.) developer probably won’t need unsafe, but it’s useful for lower-level work in libraries and CLI tools, especially where performance is important.