Because it would then look like

foreach my $file ( map  { $_->[0] }
                   sort { $a->[1] <=> $b->[1] or $a->[0] cmp $b->[0] }
                   map  { [ $_,  (stat)[9] ] }  
                   @files_Test_flat_file_write_over_name_only
) {
   ...
}
[download]

which is a bit more messy.