In paragraph #1, I advocate looking at your algors and to be watchful of overhead (and overhead that might be in your .NET application).
In paragraph #2, I categorize myself as a "system" programmer ... and if you watched the vid then you would understand that "system" (later "gamer") level programmers might not benefit from this technology because they claim themselves to be in their own infancy.
In paragraph #3, I mention that "we" (not you) need this extra performance, I agree that this is not for everyone, and I state a fact that Microsoft itself knows in that: if you can't keep your system-level applications competing then people will go elsewhere (that's the whole windows/*nix debate).
In paragraph #4, I encourage PCP further development and would even like to use the PCP->CRT and would like to see performance reports (especially if there is GPU) because companies like mine need every ounce of performance we can get.
In paragraph #5, I echo the vid in voicing that system/game-level programming requires more than most .NET (of which I find to be hype).
It's in the last paragraph where I discuss my disgust with people who do not, in your words, "use the right tools for the job and assume [.NET] is the best tool for everything". It's not my job to "crank" code but to get it right the first time (or really close) and ensure that performance is at it's peek. You argue your ability to make a web app or windows gui versus "system" programming. It's not the same ... and if you think that creating services, oil/gas calculations, live traffic projections, isapi extensions, and the such are equ to a SharePoint application then hopefully you understand now that they are not.
PCP, in my pov, is being designed for me, for my team, for my company. Within the two groups that need PCP you have: 1) people who don't thread or need performance but want a magic bullet, 2) people who do this by hand all day long to get the best of the best and would love to have some relief with hardened/tested/proven code/runtime/libs. I am the second group, but don't be upset with me if you are in the first because these tools are being designed for you too. Will I want to hug/kiss these people who might actually make a multi-core compiler (especially for my 'C'/MASM), yes!
.NET has it's place. It's the more-than-luke-warmest technology on the market today! It's not for my industry. I would love some help with multi-core but for us to use it we would need to prove that it's faster than what we have today. For me, .NET is a cool prototype too. In that capacity it *is* the best tool because prototyping in MASM is not always a good first choice.
Lastly, please note that ISAPI, Windows GUI, NT Services, other MAPI and API are all pretty easy with MASM once you get used to them. Just like anything else, you create a set of helper functions or tools that assist and you create project wizards that help with the creation. It's just like anything else really.