[Darvin]

Typically "injured" units are weak enough as it is. If you look at fast-paced games like Starcraft and Warcraft, they're often regarded as "casualties waiting to happen" and killed off so as to free up population points for a fresh unit. Even though they still are fully functional, they are still massive liabilities. While it may be realistic, I don't think giving penalties to injured units is good for gameplay in RTS games (and many other genres, as well). It grants too much of an advantage to someone whoever can perform a "first strike" and makes healing abilities so critical as to make them the central component of the game.