No. You either design the site to be fully responsive (which would necessarily include CSS changes), or leave out that line. If your CSS assumes a desktop layout, it is strictly better not to set the viewport width to device-width so that the mobile browsers will use the traditional desktop viewport and the user can zoom around without anything broken. In contrast, carelessly slapping that line without CSS changes will often lead to content being clipped and invisible on mobile. This is why I have a bookmarklet to delete any viewport meta elements.