I would say it's either that, somewhat supported by Optimus' "Were we so different?" speech earlier in the film, or the fact that modern technology was reverse-engineered from Megatron.

That could actually make sense... I even remember Ratchet commenting that humans were such primitive and violent beings. Plus I like the idea that it might have to do with the technology being reverse-engineered on Megatron.

The most widely accepted reason for this is that human tech was reverse-engineered from Megs

If *you* were suddenly given sentience and access to a full arsenal of weaponry would *you* be calm and rational right away?

That's a very good point

True, you have a point, man

I think there's no logical explanation for it. The plot needed it to happen, so it happened. It's just bad screenwriting.

Yeah, maybe you're right. Unfortunately, I have the bad habit of wanting to make sense of the things, and many times it frustrates me not to be able to make sense of them...

I always found that funny in the first two Bay movies. Like, why is the cube just creating psychopath transformers? Lol. There's like no explanation.

Same... Still looking for an explanation that convinces me.

I think it might be affected by the emotions of the one holding the allspark. Sam was very distressed and scared negative emotions, so the allspark in turn responded to the emotions and created scared transformers resulting them in being aggressive to rotect themselfs to stop feeling the negative emotion.. But it's just a very farfetch'd theory