I rolled initiative, so I have a license to kill?
So you wander in to a restricted area in the forest, say near a prison or something, a group of guards on patrol comes across your group in a hostile manner(That's what good patrol guards would do). You win init and kill a guard before any questions are asked. Without any information, no knowledge check, no fore warning? If you don't take the time to assess the situation you reap what you sow. Jail? Fines? Execution?
Blame could easily go both ways.
-Nervous and inexperienced GM, (How does a gm get experience anyways, I got better by running some terrible games and yes messing up some times. My vote is to work with the GM, build them up.)
-Blood thirsty players who think they are playing World of Warcraft and when combat starts they have to attack what ever is in front of them. Your not playing a video game, when combat breaks out you have other options besides killing what ever you just encountered and taking there stuff.
It all depends on the situation. So roll initiative, just don't think you can kill anything just because it is there.