The issue is this: Our desktop processing requirements are actually slowing and as Linus points out, are probably ill-suited for increased parallelism.
Depends on the desktop requirements. I think he is off the mark here. Specifically to quote him from TFA:
The only place where parallelism matters is in graphics or on the server side, where we already largely have it. Pushing it anywhere else is just pointless.
Since he points out servers and graphics as largely solved, I assume he is talking about desktop usage. In this he is assuming a standard usage model for a desktop user, a set of apps - web, devel, coding, games, whatever. I think the view is that of a user who can only focus on a single-task at a time (with perhaps background OS tasks). But this is a myopic view, the rise of virtualization has enabled a convergence of hardware onto a single machine. This is only possible with the rise of multi-core/parallel computing. VMs are a huge benefit, in terms of power/area efficiency and even being able to create and destroy them on a whim.
On my desktop machine (8 core) I have two VMs running all the time. These machines used to be physical separate machines, consuming power, taking up floor space, making noise, etc. I could not have run this setup on my previous single/dual core machines. However now they are virtual, and my normal desktop usage doesn't even notice them running (even heavy 3D gaming is not lagged by these VMs).
There are compounding parallelization factors - having the whole setup on encryption means wanting the cores to handle AES in hardware, so as he points out having hordes of parallel weak cores might be pointless for that. However, multiple powerful cores, I can put those to work.
IMO the advantages are clearly obvious. Sure for a single-task desktop user, you may only want a few cores for background tasks plus the foreground task. But the ability to consolidate lots of hardware into a single box, I want as much of that as I can get. I can easily think of desktop + VM scenarios that can push beyond 4 cores.