Should National-Brand Manufacturers Also Supply Private-Label Brands?

Ralston-Purina, Borden, ConAgra and Heinz supply products- sometimes lower in quality- to be used for private labels. Other companies frown upon this practice which can create confusion and/or deliver the message that all products in a given category, luggage for example, are essentially the same, so why pay more for a brand name?

How do you feel? Should name-brand companies be encouraged to offer products for sale as generic or store-brand products or not? Okay for some, but not for others? How would you feel if you found out that your favorite brand could be purchased at a lower price, minus the label or tag?