I honestly don't get it. They call the game a MMO, which we all know it's not and try to use that as a guise to make it always online. They could just have a single player mode then have online worlds that you can jump in and "interact" with people. Though I don't know how we would do that since theres no voice chat.

If it was offline, it would allow players to "hack" their character and gain an unfair advantage over the opposition. That's why all saves are kept on the server.
Same as with FIFA Online Pro or Ultimate Team (first example I could think of). Used to be you can use your offline Pro to play online, and pretty soon everybody had a level 99 player.

My guess is because Activision gets a % of the online subscription fees.

because then youd need to work in seemless transition between offline and online, and npc stock would need to be updated by frequent patches, events would require patches, and public events wouldnt really work anymore.
strikes, raids and weekly/daily events would be unplayable for most people

and honestly, the best part about destiny is playing with other people.

I don't ever think they ever called the game a MMO.

I'm pretty sure they did. And if they didn't then what's the point of being always online then?

I guess its to do with the fact they want to support it for a long time and alot will change in that time so they want to make it simpler for the user maybe

Avoid hack character, reduce pirate software, maybe fee from plus and glod, they want community etc2

To have DRM without calling it DRM.

It's all about control and having the ability to spy on consumers. Having an only online game ensures total market research.