I mean I understand their anger. If you've invested in a company and game for a long time it does kind of feel a little upsetting that so much is being done and you can't be apart of it because of your console choice. So this news doesn't annoy me.
Microsoft fans haven't invested anything in Destiny yet. Just because you bought a developer's last few games doesn't mean they owe you anything. They aren't your friend, they are a business...
I'm pretty sure Sony paid for everything exclusive and Destiny related they're getting. Seems like Sony will be doing a lot of the marketing as well..I guess Bungie also realized that overall PS4 is the superior console,that's why the alpha (and beta?) are on Playstation first.
All I can say to those gamers is, "tough cookies." Gamer entitlement these last few years has become completely absurd. Gamers want people to look at them differently, want to be respected and what their hobby to be adored and understood; stuff like this does not help.