Taking the time to debug your model of reality is bleak and unimaginative?

Wouldn't the world be a better place if everyone did that?

Can you suggest a better use for writing? I love fiction for example, but people becoming less wrong (and by extension, more skillful in the world) seems like one of the most valuable ways for people to spend their time.

As a fellow lover of fiction, I agree that there is nothing offensive or unimaginative about viewing writing as a way to deeply understand and consolidate your knowledge about technical material. I think writing of any kind is about processing information. In the case of fiction or poetry, this may be more about processing your emotions, or a profound life experience, or a cultural heritage, or a set of hypotheticals. Great literature, that stands the test of time better than more pulpy stuff, often tackles something the author and many others need to intellectually process, therefore leaving you with that feeling of revelation you may get after reading a good book.

It's "bleak" to want to improve critical thinking?

The post is aimed at an audience of software developers. Tool users, in other words. It seems reasonable to me that tool users would view writing as a means to an end, rather than as an end in itself. It might help to realize that their tool use is itself imaginative. The tool users have co-opted a nominally romantic medium so that it may serve a concrete function. That's imaginative in its way: an imaginative use of tools.