In most cases, technology improves and becomes cheaper to produce. ie, a die-shrink of a CPU enables more CPUs to be produced per wafer (so lower cost), and reduces heat output whilst still delivering the same performance. Or, you get cheaper materials (and hence lower cost) on budget laptops, but the high-end ones still maintain their magnesium and aluminium chassis etc.
The 16:9 thing though was a straight forward downgrade for everyone. At work we were refreshing £2,000 Dell workstations (Dell Precision M6500). The old ones being returned had a 1920x1200 screen, the replacements we were giving out had a 1920x1080 screen. Lower res and lower cost - but cost-cutting in a £2,000 professional workstation? C'mon!
I'm fine with 16:9 in budget systems. But it annoys me when even high-end kit has been downgraded just to reduce the BOM for the manufacturer a bit.
EDITED: 26 Sep 2016 11:35 by DAVE!!