missing cache validator

[VirtualLaw]

GTMetrix / Page Speed complain:
The following resources are missing a cache validator. Resources that do not specify a cache validator cannot be refreshed efficiently. Specify a Last-Modified or ETag header to enable cache validation for the following resources: ico, woff.

W3TC adds this to the htaccess:

<FilesMatch "\.(bmp|class|doc|docx|eot|exe|ico|webp|json|mdb|mpp|otf|_otf|odb|odc|odf|odg|odp|ods|odt|ogg|pdf|pot|pps|ppt|pptx|svg|svgz|swf|tif|tiff|ttf|ttc|_ttf|wav|wri|woff|woff2|xla|xls|xlsx|xlt|xlw|BMP|CLASS|DOC|DOCX|EOT|EXE|ICO|WEBP|JSON|MDB|MPP|OTF|_OTF|ODB|ODC|ODF|ODG|ODP|ODS|ODT|OGG|PDF|POT|PPS|PPT|PPTX|SVG|SVGZ|SWF|TIF|TIFF|TTF|TTC|_TTF|WAV|WRI|WOFF|WOFF2|XLA|XLS|XLSX|XLT|XLW)$">
    FileETag None
    <IfModule mod_headers.c>
         Header unset ETag
         Header unset Last-Modified
    </IfModule>
</FilesMatch>

Question:

This setting was recommend by askapache a while ago, but isn't recommend any more. Could the "Header unset Last-Modified" be removed?