The only reason I have not defaulted to jj already is the inability to be messy with it. Easy to make mistakes without "git add"

You can be messy. The lack of an explicit staging area doesn't restrict that. `jj commit` gives the same mental model for "I want to commit 2 files from the 5 I've changed".

But you do have the op log, giving you a full copy of the log (incl. the contents of the workspace) at every operation, so you can get out of such mistakes with some finagling.

You can choose to have a workflow where you're never directly editing any commit to "gain back autonomy" of the working copy; and if you really want to, with some scripting, you can even emulate a staging area with a specially-formatted commit below the working copy commit.