When design becomes a standard, is its purpose not lost?
You can think about it as of Twitter Bootstrap for government websites.
The application in this case is the U.S. Government. The purpose of this design is to provide the lego blocks and framework for developers and designers to build an interaction layer for the federal government.
That's not because its purpose is lost for design conformity, but because those are peak designs that work best for what they need to do.
The only purpose design for government sites has is to be able to give information quickly and in a legible and accessible way. No artistic ambitions here. That can be standardized very well.
Except that's the point of the OP's comment. These items actually do not have any explicitly declared standard like this design standard published by the government. Design became standardized through people landing on a good design, not through a government mandate.
I don't think that that's his point -- I see this as orthogonal to whether there is a standard or not.
The reason those don't have a standard is merely because they are so simple they don't need a full document to describe them.
And I don't see a clash between a "goverment mandate" and "design", since in this case the government mandate is exactly a design, that is, the work and output of a set of designers working for the government.
It's not like some random bureucrat that knows nothing about the web created the standard.