This is a fantastic read, and I agree with what you've written. What I want to challenge though is: I think you and I have different definitions of "Principal Engineer". What you've described as ideal is absolutely what I want to see in a Principal Engineer. I was a Principal Engineer at Amazon for 6 years and I have been a Senior Staff Engineer at Google for 2. People at my level, in both companies, were absolutely expected to do the sort of things you describe as desirable. Other than that, fantastic article!