I find dependencies to be a very good indicator for how my code should be modularized. That is, rather than pulling a boatload of dependencies into "the application", pull a couple dependencies into a module, and then depend on the module. It makes it very easy for dependencies to be a "well, it gets the job done for now, and I can reimplement that myself if that changes" sort of thing.
I found this approach to work well for me as well. It has payed off many times. I try to wrap most of my dependencies so that if I later feel like I need to pick some low-hanging fruit I can implement some of the functionality internally while maintaining the original api.
Also, this is probably the single biggest difference for me when working with a static vs. dynamically typed language. With Static Typing, there's a "translate the dependency's types into the application's types" step that pretty much screams "put a seam here!". With Dynamic Typing, it's a bit less loud.
I was referring to that, with Scala, I like to avoid leaking the innards of a JSON serialization library in the code for an API client, instead returning domain objects. Whereas with, JS or Python, the initial approach is to sling around the blob of JSON.
