Considering the high resolutions seen on moderate sized tablets I can understand why the limited number of tile rows (7 max) would make sense. However, the Start screen would be easier to configure for my many productivity programs on a 24-in 1920x1600 monitor if there could more rows of tiles. 8 would fit nicely, perhaps even 9. Even better would be to be able to use the more icon-like "tiles" of the All Apps screen which would go a long way towards easing the pain for the power user's loss of the Start button.

See this tutorial for how it works:

Start Screen - Metro Apps - Change Number of Rows in Windows 8