Maybe Dell just doesn't understand customers anymore?
When I read about the declining use of desktop PC's, I often wonder if fewer people are actually using them, or if more people have simply taught themselves to build their own rigs or upgrade the towers that sit beside their desks? The last time I bought a desktop outright was about 1998. Since then I've built several, and usually have a few around that I'm upgrading or modifying.
The main reasons I do this are: 1. it's easy to teach yourself; 2. I got so sick and tired of HP and Dell and Sony and IBM and others sticking me with overpriced proprietary components, when the standard gear at the local electronics shops were often 1/4 the price or less and worked as well or better.
If a company like Dell were to begin selling laptops that were truly upgradable with standard, affordable off-the-shelf parts, I'll bet their sales would take off again.