My opinion, something I'm an expert on!
Sears was the store of middle class America back in the 40's 50, and 60's and even some 70's. If you needed a washer, dryer, refrigerator, tools or tires Sears was THE store to shop.
Sears was a generational store and not only that they were the only game in town that sold everything you need and quality products. Catalog sales were a huge part of Sears and something the customer liked and relied on. Eliminating this was one of the biggest bone headed move they made. Sears felt that the catalog shopper would be forced into visiting the store and buying additional items...they were wrong...
Through the 70's, 80's and 90's Sears quality went down hill dramatically as many of it's suppliers were using Chinese suppliers and the focus went from quality to quantity. The philosophy of profit before customer and quality is a ticking time bomb for any company. This combined with huge competition has made it difficult for Sears.
Craftsman was a name synonymous with quality. Hand tools had a full lifetime replacement warranty and their power tools were first rate. As I mentioned above, the 70's were the beginning of the end for Craftsman power tools.
Craftsman lost it customer loyalty and support. This combined with demographic changes and stiff competition made it easy picking for brand names like DeWalt, Makita, Porter Cable etc to come in and take over as front runners. This is the very reason you see these names on the shelf at every Sears store...
Buying Kmart was another bonehead move in my opinion. What not buy a dollar store, their all about quality and durability aren't they?