I really don't see any reason to panic over the way the Knuffels are selling out
Personally I am buying more Knuffels now, because I'm hoping to have one in each stage that I like. In the past there were many I didn't care for, but the last ones were so cute, and I would regret it later if I bought just 1 and had to decide between 2 or more lovely stages...
Sure, it is easier to earn FPs now - no lag and I can actually dig with all my Knuffels under 60 minutes

But if I had wanted to buy a Knuffel before, I'd always have made enough FPs just by posting around polls and Spam for a few hours - so getting easier FPs isn't making me greedier for Knuffels
I guess one of the reasons why they are selling out so fast - there are simply more people playing now. With the fast feeding, the new Market, and 2 events so close after each other, the site is livelier - I've seen more newbies these days than I can remember ever seeing.