This is a safe design.

nullglob would be the safe default for commands that are void when argument is void. This is not the case whith ls.  nullglob is useful in scripts, but is not safe unless you replace ls by a function like this :

myls() { (($#)) && ls "$@" ; }

So you have the expected result when you do this :

shopt -s nullglob
myls empty_directory/*

Designers have taken the safe option, because many commands take implicit value when no argument is given, often giving a behavior that is not consistent with the semantic of nothing.

When you design a language default, your priority is to take the option that would cause less unexpected behavior, and you prefer to rise exception than doing unexpected things.

You can verify this, as soon as you set nullglob in a rich script with unexpected input variation, it may become unstable. It is like a false good idea in fact, unless you spend more time making preventive debug.

This design incorporates a safe approach, considering the use of nullglob as the default for commands that yield void results when provided with void arguments. However, this default behavior may not be ideal for commands like ls. While nullglob proves useful in scripts, it is not entirely safe unless ls is replaced with a function, as demonstrated below:

myls() { (($#)) && ls "$@" ; }

This ensures the desired outcome when employing nullglob:

shopt -s nullglob
myls empty_directory/*

When designing a language default, the priority is to adopt an option that minimizes unexpected behavior. Opting for exceptions over unpredictable actions is preferred.

It's essential to note that introducing nullglob into a complex script with unpredictable input variations may render it unstable. In practice, it could be considered a seemingly good idea that, in reality, requires additional time for preventive debugging.

This is a safe design.

nullglob would be the safe default for commands that are void when argument is void. This is not the case whith ls. nullglob is useful in scripts, but is not safe unless you replace ls by a function like this :

myls() { (($#)) && ls "$@" ; }

So you have the expected result when you do this :

shopt -s nullglob
myls empty_directory/*

Designers have taken the safe option, because many commands take implicit value when no argument is given, often giving a behavior that is not consistent with the semantic of nothing.

This is a safe design.

nullglob would be the safe default for commands that are void when argument is void. This is not the case whith ls. nullglob is useful in scripts, but is not safe unless you replace ls by a function like this :

myls() { (($#)) && ls "$@" ; }

So you have the expected result when you do this :

shopt -s nullglob
myls empty_directory/*

Designers have taken the safe option, because many commands take implicit value when no argument is given, often giving a behavior that is not consistent with the semantic of nothing.

When you design a language default, your priority is to take the option that would cause less unexpected behavior, and you prefer to rise exception than doing unexpected things.

You can verify this, as soon as you set nullglob in a rich script with unexpected input variation, it may become unstable. It is like a false good idea in fact, unless you spend more time making preventive debug.