Reading all the posts about Ash shooting Wrex on Virmire makes me want to play ME1 again to this point, just to see this scene once and make a better judgement on this. Persuasion is the very first thing I max out on my Shepards because in the end ME is still a RPG and I hate not having all dialogue options because my scores are too low, so I can allways convince Wrex, even without doing his armor quest.
Is there even a possibility for Ash shooting at Wrex if you made the armor quest before?
So, admiting I never did see the scene happen ingame, I still don't get why Ash is blamed for shooting Wrex ... it's all Shepards fault in my book. It's him not caring about a crew memeber (by not making the quest) or him not being a good leader (by lacking commanding skills he could have developed at this point) making Wrex go havoc at him. What should Ash do in this case?
Allthough I admit its kind of poor writing, that the player doesn't get it nailed to the face that it's his own fault. There should be the wheel with just two options at that point, like "all other options failed" which results in Ash shooting Wrex and "let it play out" with Wrex killing Shepard, resulting in a critical mission failure.
That's pretty much it - Ash saves Shepard from a critical mission failure, which he could have easily avoided by either paying attention to his crew or by developing his leadership skills. And Ash gets the blame for it
And I do think she's in character at that point. After Shepards ask "should I go talk with him?" She say's "Couldn't hurt, ...... well, actually it might hurt" and Shepard says: "Be ready". He doesn't say: "Whatever goes wrong, don't do anything foolish" he says "Be ready". So, what do you expect from a soldier which has been told by his commanding officer to be ready, and then the officer is attacked by an individual that is known for being: a) very skilled in combat,

able to regenerate health in seconds, c) has multiple organ backups, d) can fall into a battle bloodrage and on top of it is in its worst mood ever? Do you really think a shot in Wrex feet would have solved the matters?
I'm sure Ash was thinking about her options from the second Shepard tells her to be ready. And she (as I assume any other soldier) came to the conclusion, that if Wrex is going to attack Shepard she will have to kill him. She then chooses the most safe method to kill Wrex quick, before he can do too much harm to Shepard.
Again, don't blame her for that - she did exactly what was expected from a good soldier and she did it exceptionally well.
Final line: The reason Wrex dies is not because Ash shot him, its because Shepard failed as a commander!