I'm all for using stuff like that personally. My favorite part about digital drawing is perhaps that perspective focal point trick you mentioned- after I learned how to do similar in photoshop my life was revolutionized! Drawing cityscapes is so much easier now lol.
On things looking too stiff/using perfect lines, I think that's a matter of preference and how you want your final picture to look, and also how it jives with things that you might not be drawing with line tools. For example, if your characters have really neat and crisp line art, then using crisp lines for the background would probably look pretty good. But if the character line art is kind of loose then it might look weird if the background is much more rigid by comparison. Another thing I do like to do though is like you said here:
My line art tends to be on the looser side, so using too many automatic lines looks off in my backgrounds, but I do tend to block things out like that first in perspective and then lower the opacity and ink over it on another layer. Being able to use those lines as a trace reference helps keep everything from being too wobbly.