Welcome to the boards!

I see where you’re coming from, but try to abstract the overall effects a bit more and not let the specifics of the way the rules work with this concern you. The rules and norms in the two areas of the game just work in different ways.
To give an example of a similar case from another game system - in W40k a plasma pistol is an awesomely powerful pistol at up to 12”, yet when used in close combat it functions exactly the same as a las pistol in providing an extra attack. W40k Assault rules work a different way to the shooting rules, though they may use some of the same weapons. If a plasma pistol were to be as amazing at both up to 12” and in close combat it would probably be excessively good.
It’s the same with Epic shooting and assaults. Good shooting ability in Epic doesn’t necessarily translate into good firefight – some units are deliberately better or worse at one or other. Look at Predator Annihilators for example – at shooting they are excellent, with 3 AT shots. Yet at FF they are poor with only a single 5+ attack.
Epic has extra assault attacks with special abilities normally only applying to that extra attack. Terminators, for example, get an Extra Attack with Macro Weapon (MW) in close combat, yet their basic close combat attack does not have MW. The overall firefight ability of Wraithguard compared to most other stands is excellent though – they're one of the best firefight infantry in the game.