It's not about Sony, but consumer perception.How about a voucher?
People hate paying twice, and to them the camera is $60. I had to buy Move with an extra copy of Killzone 3 and it was really offputing personally.
Plus it's not like this only affects a handfull of people. PS Camera still sells good on Amazon and is around ~5 million sales.
I think forcing a bundle would strongly hurt psvr sales.