Why does it matter if some people are underutilizing cores on their laptop? Mine are constantly pegged (developer running a lot of different heavy processes) and I'd appreciate the ability to pay more for an upgrade. There are many others like me.

Not many enough (or not paying high enough), or there would be a market.

Instead, the major market pressure was on power efficiency.

(My cores are pegged too -- I run DAWs and NLEs -- but me and you are irrelevant in the grand scheme of things, if there are not enough of us. And that's not determined by counting us, but by the emergence of a market).