Pulling the bucket from your hands is more greed than aggression. Aggressive horses will literally attack you for getting in their space. Most often hand feeding will create a greedy horse unless it's taught, like your horses were, to wait until it's been offered.
Quiet Storm was food aggressive, still is to a certain extent. Shortly after getting her home I was leading her past some hay. I let her reach down and take a bite, and she immediately followed up with a lunge right into my face to move me out of what she considered her personal food bubble. (Thankfully, I was able to block her!) While she doesn't lunge at anyone these days, she'll still pin her ears when food comes by and shake her head. She's at the bottom of the pecking order in the herd, and none of the others bothers me when I walk out with feed in my arms, so I suspect it's something to do with her feeling she's going to miss out on eating if she doesn't assert herself. Of my three, she's the one that we don't offer treats to.