One of Hollywood's big problems is that they have to have 20-somethings in the key roles. Or at least a more mature actor who looks like one.
As an actor matures, they should develop better acting ability simply through experience, and can thus give more complex, nuanced performances. But, the target audience wants the hot **28**, so....
We're stuck with a lot of pretty faces who can't act their way out of a wet paper bag.