... the use of qq in the code you posted is unnecessary: $_ = '"$_"'; would have done the same thing.

Not so. The use of non-interpolating  '...' quotes would produce only a literal  "$_" output:

c:\@Work\Perl\monks>perl -wMstrict -le
"for (qw(help! am trapped in noninterpolating quotes!)) {
   printf '\"$_\" ';
   }
"
"$_" "$_" "$_" "$_" "$_" "$_"
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See also Quote and Quote-like Operators in perlop for a link to discussion of  qq// that's closer to the mark.

Update:

... a misguided attempt to manually escape values in a delimited file. ... it's more complicated that it might seem. ... use a module designed for handling delimited files, such as Text::CSV.

Amen to that!