Why no "each" method on Perl6 sequences?

As you wrote in the comment, just an other .map(*.say) does also create a line with True values when using REPL. You can try to call .sink method after the last map statement.

".".IO.dir.grep({$_.contains('e')}).map(*.uc).map(*.say).sink

You can roll your own.

use MONKEY;

augment class Any 
{ 
    method each( &block )
    {
        for self -> $value { 
            &block( $value );
        }
    }
};

List.^compose;
Seq.^compose;

(1, 2).each({ .say });
(2, 3).map(* + 1).each({ .say });

# 1
# 2
# 3
# 4

If you like this, there's your First CPAN module opportunity right there.