So the decision for slow interop is caused by choosing to have parity between GDScript and C# because the former forces the types to be heap-allocated...and community might dislike a performance-friendly change which will break the parity in favour of C#.
To be honest, if Godot embraces it becoming the Noah's Ark for Unity developers and prioritizes C# over GDScript to improve performance, it could be good both for Godot and C# ecosystems, and more emphasis on the ability to use very rich selection of libraries written for .NET would not hurt either.
To be honest, if Godot embraces it becoming the Noah's Ark for Unity developers and prioritizes C# over GDScript to improve performance, it could be good both for Godot and C# ecosystems, and more emphasis on the ability to use very rich selection of libraries written for .NET would not hurt either.