Why would they need to know?
Innovation and research without knowing the underlying physics is like building structures without a solid base.
I can't see why the "bubble economy" risk doesn't apply to engineering as well.
I disagree, it depends entirely on the field. A software engineer doesn't benefit in any way, shape, or form from understanding the physics of the electronics that run their code.
What’s your native language, blueskull?
The vast difference between Chinese and English is not an excuse for me not to polish my English skill.
No, certainly not! Nor did I mean to suggest that your English is subpar (it's excellent, as far as I can tell from your writing.) I was just curious because it would give me a better image of your language background. (See next Q.)
I mean, I assume you know that in English, the L in salmon is silent.
Still, it's far from "see-men".
Yes, but the reason I asked about your native language is that one's native language not only informs how we
speak other languages, but also how we
hear them. (Like how many English speakers mishear the German "ch" as the "sh" sound.)
(I studied linguistics as my minor at university, aside from being a polyglot myself.)
What did she mean by blowing? 
A (likely electrical) load.
I hope the parentheses are true. Cuz blowing a non-electrical load is also… a thing.

And why should they need to??
We are a research university, not a tech school. We are supposed to train people with a general, good and comprehensive understanding in the field(s) and expand body of human knowledge.
I don't expect details, but I would expect at least, for an ECE professor, to be able to explain roughly what a "hello world" does under the hood, down to transistor level.
I think even ECE is so broad that expecting that from everyone is absolutely unreasonable.
It’s a necessity. The amount of total human knowledge is growing at an exponential rate. It’d be literally impossible to try and learn all the stuff outside your niche.
No need to be "all". But a general understanding of everything related to the circle one travels is not too much to ask for.
Yes, but I doth declare that I suspect your meaning of a "general understanding" is far, far deeper than is realistic.