In my humble opinion, Tiffany did not ask Beyonce to be in an ad. It was the other way around. I think Jay-Z insisted on an ad with Beyonce wearing the Tiffany necklace.
The ad made zero sense... everything about it was wrong, and it was so opposite of the Not Your Mother's campaign which just rolled out a bit earlier. The timing was completely off, almost as if TIffany had to rush to get the Beyonce ad out.
To me, everything about the ad had Jay-Z's fingerprints all over it. I can see him having a lot of input to it.
Yes, they are a cute couple, but they are also publicity hogs.
Here's what I think... Lady Gaga wore the Tiffany diamond and got so much publicity. Beyonce got jealous and wanted the same.
If you recall, Jay-Z recently sold his champagne brand, Armand de Brignac, to LVMH. Price was about $600M. I would bet as part of that deal, Jay-Z said to LVMH, "get my wife in an ad, and let her wear the Tiffany diamond, otherwise, no deal."
I can totally see Jay-Z doing that.
Every Tiffany ad has always tried to sell something... DBTY (Christy Turlington), silver pieces (Not Your Mother's), etc... The whole point of Tiffany ads is to enable you to want to buy that item, the DBTY, or the silver cuff bracelet.
This Beyonce ad is selling Beyonce, nothing else.
Anyway, that's my little theory.