Fair enough. I still think the vast majority of what I see in Nature Biotechnology is head and shoulders better than what rolls through Bioconjugate Chemistry or Biotechnology and Bioengineering . If you want to argue about JACS/Angewandte Chemie vs. Nature Chemistry, sure I'll take a solid JACS paper any day. But if we're talking about top tier journals vs dead average ones, high IF journals still provide:
1) ideas that are (typically) more meaningful to the field and researchers outside of the field
2) a higher bar for reproducing data (i.e., reviewers ask experimenters to reproduce the results, often in subtle ways)
3) superior collective post-publication vetting (i.e., far more eyes on the research to reveal potential fraud)
I simply trust these papers more. I've reproduced methods from Cell, Cancer Cell, Nature Biotech, and other similar journals with a high rate of success. I can't say the same for lower tier journals.
To your point about tenure committees, that is definitely not true at my PhD alma mater. It was basically a requirement to get at least one last author publication in a prestige journal. As an example, one professor with about 35 papers in 7 years in solid journals (IF ~5-10), about half of those as last author, was denied tenure. The next year a professor with only 10 papers in 8 years was awarded tenure. However, the second professor published 3 last author papers in journals with IF > 40. In the last 15 years, it's been a de facto rule that a paper in a top journal (e.g., CNS, Nature Biotechnology, Cell Stem Cell, etc...) is required for tenure in this department.