> the text is just a tool to manipulate some abstract model of the program.
yup.
> When you think about it this way, it becomes clear that using a textual source code is really inefficient way to manipulate this model.
Hard nope. All the attempts at different approach were a failure so far. Text so far is the best thing we have because text can be analyzed formally and computed with by computers. This is the result of the work that's being going for at least like 200 years in philosophy, logic, and math.
What we really need is to bridge the gap between programming and math as industry standard, not academical exersise somehow. But I highly doubt eliminating text as source code is it.