It was increased, because people were farming reputation on the city guards in Booty Bay and since they were too easy to kill, one of the harder parts of an Achivement "Insane in the Membrane" was super easy if memory serves me correctly.
I agree with Markux that they hit waay too hard and if they focus on one person, who won't get help, there is no way he/she can survive unless it has great self-healing abilities. There are 100k+ hp mobs in Northrend that can be easily killed, but if you get 2 city guards for example while getting Explorer title in Darnassus, there is slim chance of you getting out alive, unless you have bubble or vanish or invisibility etc.
However I also understand why the Staff of Warmane sees this as non issue. I mean a lot of city raids just breeze through to the faction boss since most are done late at night and city is practically defensless since players are either asleep (offline) or doing stuff. Still this is an issue, because from my experience, getting to for example Thrall, who is the most important of Horde bosses in this expansion is pretty easy compared to the path to King Wrynn which has guards every other step compared to few in Orgrimmar.
And one thing. Bosses used to be a challange in itself in retail. Here they are tank and spank. I mean c'mon 2 people are enough to kill faction bosses if they get past city defenses. Been there, done that.