I have to disagree with you there.
I've played MMO / RPG type games where once you leave the confines of the "safe" zone in the city, its essentially a free for all where you can PVP or PVE in the same zone.
Not a fan at all and much prefer to have PVP in a separate crucible arena and be able to play PVE on free roam where nobody can grief me. I've also played games where they have open mics and I'm not a fan of this either. You just end up getting people chewing their mikes, blaring music, shouting at their kids / pets etc.. and theres either nothing you can do about it, or you have to set about muting everybody making nose one by one.
The free roam system on patrol mode works just fine for me. Everybody is free to play how they want and nobody can touch anybody else. Quite often you'll find these players start to work together like in the public events.
Destiny is hugely popular, and I'd rather they not change fundamental things about the game I like (such as this) to go try and chasing more players, because they will just upset the existing players that have put so much effort into their characters.