So yeah, I did think about the list paradigm thing. Restrictions breed creativity, right? I'm just not sure how applicable it is in this case. In the case of Discern Realities (or AW's Read the Sitch move) it makes sense, because it's trying to avoid this mode of play:
"I search the room. That's a... 22 on the perception check. What do I find?"
But, although it looks like a restriction on the player, it isn't really -- it's using the player's choice to create the restrictions on the GM that breed the GM's creativity. And, of course, while the rules authors have tried to be comprehensive, a group might well want to add a question or two to fit their vision of comprehensive, if there is something that is important to that group that the authors missed.
In any case, I don't think that problem is so applicable here, because as I said, I think the usual mode is going to be that the Paladin has an idea of what to do and wants to frame it as Quest, rather than saying "I want to be on a Quest, what task should I take up?" Given that, I think either the one sentence formulation should be used or the list should be exanded to more comfortably cover the common cases.
Incidentally, I'm perfectly comfortable with house rules. It's just that sometimes there is some reason behind a rule that I don't see, and it's good to get other people's input on it. And it can also be good to see if there are any other people with the same issue you have...