Years ago, I played UO and enjoyed it.
For all of 5 days. Then it became a cringe-making hell for me.
Unless you were one of the uber-elite of gamers out there who knew how to level to demi-godhood on the servers, you were their prey.
The game became less and less fun the more I tried to simply to do something...anything to get better than a lowbie character, the more frustrating it became. I tried mining, and was frequently killed for my hard work. Logging, anything...I was a target for players who wanted nothing more than to kill and enjoy the sweat off of their victim's brow. I couldn't earn money, couldn't advance...
In fact, the only thing I was great at was dying.
Not exactly something I want to sink money into month after month. After 15 days, I gave it up as a bad idea.
Everquest came along with something that allowed the PvP'ers to have their fun and would leave us casual players to progress at our own pace. There was no real need to level to the max in nothing flat just to stay alive, one could enjoy the game. World of Warcraft did something different, but has the same result.
Why are games going this way? Because look at the "Make Love, Not Warcraft" episode of Southpark. Once someone was able to kill at will and in fact seemed to get off on ganking lower-than-he characters...people stopped playing the game. The Fictional Blizzard company in the episode saw millions of their user base turning off their computers and going outside to play.
The real Blizzard and other companies running MMORPG games would have a very real version of this problem. In fact, once EQ came out, people jumped from UO to it and most of them said that EQ was far superior not for graphics, or world development...but for the simple fact that they could PLAY the game and not flee anything that was controlled by another player.
That's why everyone maximizes game play and leaves options for people to decide to play PvP without interfering with everyone else who doesn't want to play that game.
Sure it sucks for the PvP'ers, but that's why there are PvP servers. If you want to be that kind of player...there's your world to do it in.