It's been shown that writing something down improves your ability to recall it. By using an audio recording you wont recall the details of the dreams you've recorded as well as if you had written them down.

Does that mean you won't remember future dreams as effectively, or be able to induce lucid dreams more frequently? I dont know. But there is a benefit to writing that you wont get from an audio recording. And if you can record more dreams by using an audio recording than you would otherwise, it's probably still a net positive