* "A seasoned C developer with 10 years experience can not instantly morph into an advanced front end web application developer" - yes he can. Knowing things on bottom easily allows one to move up. It is the reverse that usually cannot happen.
* "Ignore the usual template based CV padding" - if you got the resume through an agency, it would have never made it to you without this bullshit. Sad but true
* "You often need specialists and not generalists." - false Specialists will become useless when that technology is no longer in use (you move form C# to java, for example). generalists will just help you with your next thing.
* "If you are looking for a C# or Java developer. You would expect their CV to contain those keywords, in context quite a few times." - false. If you have enough interesting things to put in your resume, there is no space to write "java" 1000 times.
* "I would expect to see some of the following throughout their CV; Design Patterns (MVC, Factories, Singletons, ActiveRecord), Classes, Objects, UML" - who the hell puts "classes" and "objects" on their resme. If i have to explain to you what OOP is and includes, I do not want to work for you!
* "Community participation" - maybe accurate. Some people do not like handing out their code for free on github, and instead get paid for it (people who contract for a living, for example). Really want to disqualify them?
* "if it becomes the next big thing, this person could be the one to keep your company at the forefront!" - If you hire based on technology instead of actual understanding (which it sounds like you do) then you will lose long term. Hire people who can actually learn, not those who happen to claim to know the latest buzzwords.
Of all the brilliant people I know, you would have discarded 100% at resume review stage. Probably not the best of ideas, that.