Although under a single umbrella, it is most likely that each brand is treated as an individual business within the organization. With their own profit/loss statement. Maintaining brand loyalty, market share, price points, manufacturing, distribution, advertising, margins, positioning of brands within a geographical area etc. all come into play with each individual brand. There are pro's and con's to this kind of business model.
Ultimately,it is the quality of the tool that maintains brand loyalty. Sears did not fail to realize this, what they failed to do is maintain it!. As their market share dwindled (primarily due to growing competition and online sales) so did the profit. To maintain margins and profit they sacrificed quality. This worked in the short term for those making the decisions and they personally gained from it, however they had to know full well that in the long run it would not last and neither did they. I believe they milked the name for all they could, padded their personal accounts handsomely and then got the hell outta Dodge. The last few years has seen a slow but steady resurgence in the quality of the Craftsman brand, hopefully B&D will continue to grow it again.
"..... limited only by imagination"
"Just smile and wave boys, smile and wave"
Skipper the Penguin