Others venders are doing it for laptops even smaller. Keep up with the times.
Show me a 8 core 15/28W 13" laptop. I don't ever recall seeing one.
Only machine I can think of is this thick beast with a 35W AMD chip:

ASUS United Kingdom
ASUS is driven by innovation & committed to quality. It is a maker of the world’s best-selling, most award-winning laptops, motherboards & graphics cards.

And it's chunky to help with the thermals.