I saw it too. I didn't think the first half was that bad. We send similar precise requests to grandparents. I also didn't have a problem with saying that the kid already has X number of books, thus they don't need anymore. We have done that too. I mean if your 2 year old already has 10 pairs of footie jammies, it makes sense to communicate this to close relatives. But I'm still unclear who they sent this letter to. Just grandparents? This type of specificity is only appropriate for close family. If they sent specific requests unsolicited to friends, it was not cool.
By any measure, the second half of the letter, however, was beyond the pale. If you are going to return a gift, you absolutely never tell the one who gave you the gift or ask so forthrightly for a receipt. You say "thank you very much" and return whatever you don't like. And the part about using the proceeds to buy formula? Tacky, tacky, tacky.
That letter overall was a major breach of etiquette and deserved to be skewered. It was tactless to say the least.