All the normal quest depend on you to be a merchant because they get 10 percent discount while ranchers get 10 percent rarity increase in hatches which is only useful in kirs quest but there needs to be less hard quest or seasonal ones 

Patrick confirmed that there will be another pet quest at some point:
http://www.rescreatu.com/forum/cat/feedback/suggestions/one-time-event-to-seriously-raise-the-value-of-creatu/~page/2/

Although with most Quests, I think people often buy from other users instead of lurking in the shops for their item, so it doesn't make much difference.
Although you pointing that out does make it seem unfair. xD