"I know the view of Starscream as stupid is very popular, especially among male fans"

That's an interesting point - why is it female transfans think one thing about Starscream and male ones think another (namely, "yeh dumb arsegike!")?

As for how he remained such a high-ranker, I figure it for a cross between him having some tactical competency and Megatron wanting to make sure he knows for a fact where the most likely backstabs & coups will come from.