Why is Lenovo so obsessed with thinness and weight?

Considering the T/X series, I find it frustrating that if you want a premium machine with high quality materials and components, you HAVE to go with something like the X1C or the T14s. They are both primarily focused on being super thin and light, compromising on performance and thermals.

If they could make a thicker version of the X1C with better thermal headroom and a higher TDP I would be all over it.