Actually, engineering is all about trade offs. Good engineering is to understand the trade you are making, and be consistent with it, and playing to its strengths.

For example, Linus Torvalds is an excellent engineer. So in the Linux kernel, he understood the trade off between modularity and simplicity/performance. That's why he did not choose microkernel architecture. He also understood that device drivers often require weird changes due to hardware evolution, that's why he decided against having too many abstraction layers in drivers (which would be better according to DRY rule).

Similarly, in Git, he decided not to use delta format to store changes. This takes more disk space (which is cheap today), but gives improved performance. Again, he understood the trade off, and concluded that performance is more valuable than disk space saved.