This is essentially how I feel -- GC by default with user control over zero-copy/stackalloc behavior.
Modern .NET isn't even difficult to avoid allocations, with the Span<T> API and the work they've done to minimize unnecessary copies/allocs within the std lib.
(I say this as a Kotlin/JVM dev who watches from the sideline, so not even the biggest .NET guy around here)
Note that even Rust's success, has triggered managed languages designers to research how far they can integrate linear, affine, effects, dependent types into their existing type systems, as how to combine the best of both worlds.
To the point that even Rust circles now there are those speaking about an higher level Rust that is supposed be more approachable.