Hello World doesn't benefit from that 12MB. Your real app would.
12MB is not for Hello World. 12MB is for Hello World + Common Language Runtime (garbage collection, bounds checking, memory protection, execution environment etc.) + the .NET standard libraries (LINQ, task parallel library, etc.)
You're probably going to need those things in a real app.
If you're actually doing Hello World -- and that is all you're doing -- and if using 12MB of your 16GB of RAM is unacceptable for you, yes, by all means write some native code.