Same issue here, the caret is not clickable (unless zoomed in) on touch screen. Ideally, it would be great to have it so that the first tap opens the drop down and second tap go to link in the cases where parent item is a link. Users won't think to tap caret in its current form, as it doesn't look like a button, it just looks like a symbol to Indicate that the menu is a dropdown.
Thanks! 🙂