I was also confused by the seeming schizophrenia in this article. It begins sounding like a condemnation of slimlining, but then seems to hail the rather marked improvements that manifested in the SP and the DS Lite. I suppose then that a reasonable, but rather obvious, conclusion that is slimlining for new or better features is good, slimlining as a cash-grab is bad.
Most pronounced to me was a rather stark lack of technical considerations in this article. Part of the reason why new console are bigger than the old ones is that miniaturization is expensive. For example, it is technically possible to incorporate that massive power supply into the XBox 360, but it's going to increase the price quite a bit (especially if they want to keep the form factor relatively the same). Hardware design is almost always constrained by price. Hardware designers and engineers do the best that can, but they still have to ensure the units costs less than $400 (or whatever) to produce. Given that limitation, it's simply not possible to incorporate all the features you want. We can certainly take issue with the decisions that are made, but acting like no compromise was required, but rather features were absent simply due to neglect or oversight is naive.
But technology marches on, even when it isn't time to release a new console. Features that were previously too expensive to incorporate are now fiscally viable. One important consequence of Moore's Law is that every two years, transistors take up half as much space as they used to. It's not as if Nintendo forgot the lessons they learned evolving the GSA into the SP when they were designing the DS. It's simply that due to the ultimate constraint of cost, some things had to give. A year or two later, however, prices have come down and features that were not available due to price can be incorporated. Previously unseen problems have been discovered and corrected.
I work in mobile software development and this is something the mobile handset manufacturers deal with all the time. Nintendo/Sony's slimlining is child's play compared to what the engineers and designers at Nokia, Samsung, Motorola, et al. deal with continually. Customers always want more features in a phone: slimmer, more storage, more battery-life, better camera, wi-fi, GPS, etc. Unfortunately, something has got to give. If it doesn't, the phone ends up costing about $500 (e.g. Nokia N95). In a year or two, the price will drop and there will be another cutting edge handset that boasts even more features in a better form factor.
Ultimately, I'm not saying that cost is the only factor that effects these decisions, nor that some instances of slimlining aren't just looking to milk the same cow again. But more often the not, fiscal and technological constraints dominate these decisions. Finding both of these things absent in this article was pretty disappointing.
