Because if we look at a common part of laptops you find 300 to maybe 1200 cycle batteries and this means a major component did not make it to 4 years.
About the i7. While I love 'em, have you read the following?
"Our tests demonstrate fairly little difference between a $225 LGA 1155 Core i5-2500K and a $1000 LGA 2011 Core i7-3960X, even when three-way graphics card configurations are involved. It turns out that memory bandwidth and PCIe throughput don't hold back the performance of existing Sandy Bridge-based machines. "
This means a lot for many folk. Pull back to the often cooler i5 (heat reduces life span) and consider paying half that for a 2 year laptop. I picked up a Samsung rv515 for 399 and from the looks of it, it may be something I'll recommend for some folk.
I want to know if there is any computer like this:
Core i5 or i7 processor
720p or 1080p
14" to 17" display
It needs to last me AT LEAST 4 years
I would like it to have:
6+ hours battery life