I always liked Raiden the way he was, whiny voice and all. And now that I think about it, I have my own reasons for liking him even more, and I'll just say that being a soldier is not as easy as it looks and specially if you are part of a Black Ops elite group where you are to take on an entire army on your own. I'm not even on special forces or have ever had to kill a person, and find it hard to pull through the day some times. I can't imagine the trauma I'll go through the day I'll have to do that, I'll probably cry like a biach and puke my guts out.
Raiden had just been thrown in a situation like that, it was his first real mission, it was his first kill, it was the first time he friggin got shot at. (Then again, he pulled through all those things, kept moving forward and accomplished the mission) I know it's just a video game, but, fictitional as it is, it is also very realistic on those aspects, and the reason people think that Raiden is such a cry baby is because they measure him against Snake, and that's probably the most unfair comparisson in the world. But I bet you that if there was to be a game that showed the first days of Solid Snake's training under Big Boss, he would probably be seen as a week and whiny character.
I can't wait to see a seasoned, expert Raiden, I am sure that he will kick ass, I picture him more or less like Liquid Snake. Plus he was always more acrobatic than Snake, so that can give him some more props.
Don't make mistake on what I am saying though, NO ONE will ever be as cool as Snake (other than Big Boss), no matter how cool they make Raiden, he won't "outcool" Snake.