the point is not whether it is acceptable or not, the point is that she is a schoolgirl with no income and wants things/money so she'll accept things/money from people she refuses to engage with until she is old enough to earn her own money. Once she earns her own money, she won't need to accept things from people she refuses to engage with
Actually, the point is precisely that it is unacceptable. As a child, her DH is obligated to make sure (along with her other parent) that she has her basic needs met. He has done so, apparently. He also has apparently made sincere and multiple attempts to meet her emotional needs.
As you point out, she quite naturally wants other things. But the idea that she needs to take things from people she doesn't want to engage with? Not at all. In fact, if that is her attitude, I'd think a much more serious intervention is called for! Imagine if such an idea (I can't afford it, so I will play on the emotions and affections of others to get it) were to continue into adulthood...
Allowing her to abuse people's (even relatives) generosity and to behave in ill-mannered or hurtful ways, and still get her "wants" (as opposed to her needs) met, would be poor parenting and counter-productive, in that it puts the business of acquiring things over the parent-child connection.
Gifts can certainly be conditional. Affection and respect between the giver and recipient seem like reasonable conditions.
Anyway, the gifts are not being withheld. They are hers to pick up when she likes. The act of delivering the gifts is what is in question.