There are numerous benefits that would be lost.

In Lamdu, each subexpression has its identity that survives as it is edited, moved, etc. This helps merge changes with far fewer conflicts.

Lamdu also allows attaching English names to identifiers, in addition to Chinese names, Hebrew names, etc. This approach can hopefully rid the world of duplicated libraries where the code is nearly the same but the names are Chinese. This kind of rich metadata doesn't survive well when serializing to text.

Lamdu will also maintain(and distribute) code indexing alongside the code such that the algorithmic complexity of refactoring large projects is not O(project size). Text is not a good data structure to perform these operations.

Lamdu also maintains many invariants about the code (e.g all type errors are localized and marked as such), what would Lamdu do if you try to load text that doesn't maintain the invariant?

We also believe the entire textual tool chain could be so much better if it were rewritten to work with asts.

So for us the only value in textual integration is the "old world" of programming, and we're creating Lamdu much because of our dissatisfaction with that world.