I agree with you general sentiment. IMO $_ should be used to increase readability. For the most part explicit use of $_ is a detriment to readability.

For example, I will use $_ explicitly when I would otherwise be creating a throwaway variable:

foreach ( @array_of_array_refs ) {
    my @current_array = @$_;
    # do some destructive processing on @current_array
}

#compare to
foreach my $current_array_ref ( @array_of_array_refs ) {
    my @current_array = @$current_array_ref;
    # do some destructive processing on @current_array
}
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I feel believe that this helps reduce visual noise, and keeps the code focused on what is important. Unpacking $_ to a scalar may be used to avoid side effects due to the aliasing of loop variables.