I'm quite confused about this also, but I think we'll have to wait and see exactly how this will play out before we jump to conclusions. Maybe by single use they mean you can't combine them to make them into multiple-star magic?
OK.. Here is my honest opinion.
I was reading Yavn's newsletter, totally spazzing out, and then I see this junk.. Im thinking - what's the use, if you can only use it one time, right?? I mean, how will they be rare? The worse part, is, if u want to save it - you almost can't, bc they will expire! So now im like, what the heck?!? Something MUST have been wrong when they thought this one up..
Im sorry - Im TOTALLY against it - there may be ONE possibility to like it a BIT if the magic's any good.. but - gosh, one time use? NOT liking the sound of that..
Think about this. This once used magic pin is needed to get to a certain place to get the new magic carpet permenant pin quest, however miss the question after youve complete the once use part.. and they send you back behind to where you need to use that item again. Suddenly that becomes a lot more valuable doesnt it?
(notice i have no idea if this will actually happen. just a thought. and i have no idea if magic carpet magic is coming out. just a thought)