The concern because of this is reasonable: identification would allow voter coercion or vote buying. But I think there are two issues with this concern. The first is that our current system doesn't prevent this. Bringing recording equipment into voting booths is not allowed, but in practice has 0 enforcement or enforceability since many (most?) locations offer shielded voting booths that even include privacy curtains.

The other practical issue with this concern is that buying or coercion would need to be of substantial scale, centralized, advertised, involved traceable transactions, and so on. And this is a criminal felony so the consequences for a leak are substantial. Ultimately, it just does not seem like a realistic attack vector.

So in many ways, I would consider this a feature more than a bug. You can personally verify that your ballot did indeed get counted (at least if you're willing to dig through thousands of ballots looking for your 'secret code') without allowing anybody else to see how you voted.