IBM sold its PC division to Lenovo in 2005, so your timeframe correlates with the laptop division no longer being part of IBM.
Not that Lenovo is a bad company persay, but IBM was historically a company that focused on corporate sales and Lenovo is a company that seems to target the consumer market. As far as I can see, individual consumers are much more price sensitive than corporations. That would explain the steady decline in quality.
I'm certainly not an expert, so there are probably other valid explanations. Unicomp bought IBM's keyboard manufacturing division (or at least the equipment used to build model M keyboards), and experienced a decline in quality simply due to (allegedly) not updating the old tooling until fairly recently.
Not that Lenovo is a bad company persay, but IBM was historically a company that focused on corporate sales and Lenovo is a company that seems to target the consumer market. As far as I can see, individual consumers are much more price sensitive than corporations. That would explain the steady decline in quality.
I'm certainly not an expert, so there are probably other valid explanations. Unicomp bought IBM's keyboard manufacturing division (or at least the equipment used to build model M keyboards), and experienced a decline in quality simply due to (allegedly) not updating the old tooling until fairly recently.