While it may be perfectly acceptable to ignore the lower-level details when first learning some new technology, or even when using it for personal use only, that sort of ignorance is not acceptable when working on systems that are meant to be used seriously.
At that point, you need to have at least a high-level understanding of each and every layer that you're building upon. If you don't, then it will come back to haunt you, whoever uses your software, and whoever has to maintain it after you're long gone.
We've all encountered, or at least heard of, the Java and Ruby programmers who use ORMs, but who refuse to learn SQL, and refuse to learn how relational databases actually work. They write their software while understanding only the highest levels of the abstractions that they're working with, and then the system ends up performing horribly. Then somebody more experienced and knowledgeable gets called in, and gets to see how the ORM is generating abysmal SQL queries, or indexes aren't being used.
It's better to know and understand than to not, especially in the long term.