There is so much pressure for women to breastfeed, they have to do it every blasted 2-3 hours for their infants, and we should be more accommodating.
If the woman feels inclined, she can use a cover (I know my wife would feel more comfortable with a cover), but if a baby doesn't feed well with a cover or the mom doesn't have a clean cover or if the mom just plain doesn't want to use a cover for any reason whatsoever, then they should be allowed to feed their infant without people having a fit.
Bottom line: If society demands that mothers breastfeed their kids, I don't think it's the breastfeeding mom should have to accommodate everyone else's sensitivities on something that shouldn't be a sensitive issue.