I've never paid much attention to Star Wars beyond the movies. Stormtroopers appear in all three of the original films, and with the exception of perhaps one scene, they seem to have horrible aim and go down when hit with any kind of attack. The lowly Ewoks take out dozens of them with clubs, bows & arrows and rocks.
Moreover, they're also rather stupid. While sweeping Mos Eisley for two droids, a squad of stormtroopers comes across a locked door and decide to move on. I guess they could not concieve of a world in which intelligent humanoid droids can lock a door?
As such, I think yeah, they should probably be pushovers in the RPG, at least if the game is supposed to mirror the films and not the EU stuff, or novels, comics etc.. I don't know whether George Lucas intended them to be the elite troops of the Galactic Empire, but if that was his intent he seems to have changed his mind while filming the scenes that included them, because they come across as hopelessly inept virtually every time we see them.
In fact, one of the lines that never fails to make me laugh in Episode IV is when Ben Kenobi says "…And these blast points… too accurate for sand people. Only imperial stormtroopers are so precise."
Clearly, he has not watched Episodes IV-VI