Why? Since you are vetting the code it generates, the rate at which you end up with code you accept seems like a good measure of productivity.

1000 lines of perfectly inoffensive and hard to argue against code that you don't need because it's not the right solution is negative velocity. Granted, I don't think that's much worse with LLMs but I do think it's going to be a growing problem caused by the cost of creating useless taxonomies and abstractions going down.

That is to say: I think LLMs are going to make a problem we already had (much) worse.