Are you talking about in a gym or in a tournament? As far as for a tournament, going strong at the beginning is helpful for a number of reasons: the psych-out factor, getting into a dominant position, etc. However, as far as for gym rolling, I don't agree.
Some possibly relevant pieces of information about me: I'm 37, a woman, and a 4-stripe blue. I often find that the people using a lot of aggression in the gym are white belts - partly because they don't have the technique to back it up. Nearly every purple and brown and black I know do NOT go aggressive at the beginning. They save their energy. So when a white belt goes aggressive with me, lately my thinking has been "Okay dude, REALLY? Is that REALLY how you want to roll?" And if I have the opportunity to get on top I will go very strong - not douchey, but with a heaviness I normally don't break out on the young white belts.
I tend to use my aggression and energy to get out of really bad spots - it will often take them by surprise.
In many ways, aggression is a bit like yelling during a conversation. If you start out yelling, it sets a tone that your opponent will either shy away from or work to out-yell you. So when I use aggression during an escape, it's sort of like screaming when someone is dominating a conversation - startles them. ^_^