Nepster: Implementing it as creator-selectable per-pack should be pretty simple, really? Assuming they haven't been culled yet, you could probably just follow the example of how custom post-level jingles work.
However, overall, I'm going to guess that this will ultimately fall into the same fate as the post-level jingles - it'll be seen as a fun feature at first, a few packs might even have custom ones, but eventually it will get to the point where the default option for them is "Off". Or, the feature gets culled altogether. (Although in this case, since all that's being culled is a cosmetic feature, it's not such a huge deal.)