Not to back up what PKTKS says in general, I think he tends to be a bit too extreme in general. But here, your "facts" are only partial.
In this CPU example, sure, unused cores won't be clocked (at least, we sure hope that's what Intel implemented, as it's pretty reasonable). So they won't draw any dynamic power, but unless there's provision in the CPU to completely power down those cores - which I'm absolutely not sure of - they'll still draw static power, and for such large integrated circuits on such CMOS processes, that's not unsignificant. Sure is a lot less than when clocked at several GHz, but that's still useless power consumption.
And then, there's also just the general fact of selling products containing a big part of unused items. That's just a *waste* of material. So however you look at it, this licensing model does have inherent efficiency issues generally speaking.