When omni-crafting, you're always crafting HQ gear, so the double-ding is audio clutter. I've been doing crafting in my house, but I can imagine what it sounds like when in a busy common area.
I've confirmed that, by turning OFF your battle effects, you don't get the cartoony fishing queues, but you still get the double-ding crafting effects.
Frankly, and I see someone said to not harp on the developers, I can only realistically describe this as lazy coding. It is literally, "we want to save time, so don't add a customization option; just allow it to be turned off with this generic battle-related setting."
Sorry, the following must be said: Unless developers spend time to flesh out a feature by thinking about how it impacts gameplay and the user interface, the coding can only be described as "half-assed." No insult intended; that's just what it is, and not appropriate for what is supposed to be a polished MMO experience.
