I think the standards letter is entirely the correct way to go. A couple of years ago I worked for a company doing nothing more than bringing their drawings into line with their company standards. The company hires about 50% of their work out to outside contractors. After a few months they realized that they could no longer manage the drawings because of the wide variation in the "correctness" of the drawings, and consequently had to hire me (and a few other folks) to fix the drawings. Personally I don't see it as a pissing match, I see it as a "I am paying you to do 'this' and if you cannot or will not do it, then someone else will" period. It isn't about trying to force someone to do something extrordinary, it is about consistency.
I suspect if I ask a hundred different people about a specific layering scheme, dimension standards, text size etc.. I would have at least a dozen different answers regarding how it should be. The bottom line is that the standard that best suits your needs should be the one that you adopt and use without regard to the needs or standards of other people. That being said, if you work for a company, either as an employee or contractor, that company has the right to demand that you follow their standard, or find someone who will.