Code navigation is hard in plain text editors, but definitely doable. I think the cost of setting up code navigation and jump-to-definition in Emacs is lower than the cost of dealing with how slow and bloated IDEs are. But, hey, to each his own.

Although I think Light Table is trying to be like what you're saying, incredibly liberating in it's ability for code navigation. But it's still young.

As for type annotation and static analysis ... you don't need to have static analysis for what you're talking about. Yes, static analysis works best for static languages, but you can have code auditing in dynamic languages. An auditor can dig through and profile your stuff while tests are running and learn about interactions between various entities in your code. And if you're doing anything in a dynamic language properly you're doing a lot of tests.