Nope. Parsing isn't even necessary for most things I want to do. Moreover, I don't really care for trees: any objects, any structures, any source can be used. There will be a common interface for it (like jump to the next semantic unit or search a lisp object). But any object can have it's own programmatic interface, and not all objects need to implement all of the interface (e.g. a read-only object).
I have expounded the point about structural editing (tangentially) on some other comments here, in this top-level thread (unless you want to read the article [1]).