Actually I am claiming that detailed knowledge of old things has never been "in" to begin with. HN seems to harbor a great breadth and depth of knowledge and I don't think it represents normality in our industry.
Failing fast is nice, but a more measured approach might result in less of it. When it comes to storage and email, people are surprisingly unwelcoming of failure at any speed. If a little study can avert a few catastrophes it's worth it. I think ours is probably the only industry that would question the wisdom of study.
By positioning history as in conflict with raw experimentation, naive excitement and all the rest, I think you're engraving the line in the false dichotomy. Is a week or two of research sans coding really such a high price to pay? Personally, I find there are a lot of really inspiring ideas in old stuff, ideas that strike me as newer and more exciting than "embed Javascript in X."
Are young developers' egos really so fragile they can't weather having someone with experience say "fsync should be on by default"? Is cracking open the source code to BerkDB really such a deflationary moment that it threatens our industry's progress? I, personally, think they can handle it.