(I just played DS Cute. So I don’t know why I drew the boy. But this is what I got from it.)
The Witch Princess poofs in at random milestones, offering you a tangible but meaningless reward. It’s a gift item that sells for next to nothing and that she freely admits is totally useless. …But hey, at least it’s something.
The Harvest Goddess poofs in at random milestones, offering you absolutely nothing. She makes a big show of pointing out that you get nothing. …Except maybe that fleeting opportunity to take some pure pride in your achievement.
Such a big part of Harvest Moon games is self-motivation. …Finding ‘something exciting in this world’ that only you can see amidst all the repetitive ‘patterns.’ Being willing to work hard for your own personal satisfaction and little else. I think that’s the takeaway message. So in that way, as annoying as it is to be constantly denied rewards, I think the Goddess is supposed to be like the ‘good angel’ on your shoulder reminding you that hard work is its own reward~.