Although I agree with the notion that deep knowledge of complex systems has decreased over the years, I'd argue that the problem isn't the lack of interest in gaining deeper knowledge that's the problem, nor a perceived lack of respect for expertise.
I'd argue its more to do with the nature of how large codebases morph over time as they're retrofitted to do more usercases. Its a lot easy in the short term to just hack in the functionality you need into an existing codebase, instead of rewriting the entire thing from scratch every time. This comes at the cost of maintainability and leads to a lot of headaches in the long term, as systems that where never designed to work together clash in unexpected ways.
I don't begrudge anyone for not wanted to dive into codebases like that.