I do wonder how much they actually save with all this wire bonding.
If you dont know, it means that it is not relevant to you. I imagine, below 10K pieces it is not really worth it. Also, it will not be worth it, if your system consist of more than 2 ICs on the board. I mean, COB for sure will have lower yield than SMD, and if you have, say 4 chips on the board, the economics are probably not working anymore.
So if you are not designing single use singing greeting cards, dont even bother.