Neither of those factors play a role: there are plenty of 27" televisions, and it's not the resolution that matters, it's cutting the glass. The official Lenovo blog talks more about this: http://lenovoblogs.com/insidethebox/?p=220
Apols for the depth thing, don't know where that came from. Possibly reading about bit-depth, another traditional area of Apple cost-cutting.
Actually, if you read the Lenovo post, TVs are precisely why the 16:9 ratio is being pushed by screen manufacturers: there's more TVs made (at 16:9), therefore, if they maintain the same aspect ratio for all screens they manufacture, there's less waste in the glass cutting process, which means 16:9 screens will be cheaper than custom-ratio screens like 16:10..
Apols for the depth thing, don't know where that came from. Possibly reading about bit-depth, another traditional area of Apple cost-cutting.