[quote=ASTA]
Because current humanity can construct a gigaton-level nuclear weapon if it wanted to. Granted, it would be enormous, but it could be done. A civilization that could traverse between planetary systems and star systems in a reasonable amount of time is to be assumed to have access to weapons systems and power generation apparatuses of such daunting, awesome power that, to us, it would be considered nigh-magical. I guess you could say that an entirely peaceful species could achieve interstellar travel, but they could just hose you with the exhaust of their fusion-based or antimatter-based engines and more or less render whatever armor and/or shielding that you're using null and void. Placing an FTL drive on an inert object like an asteroid or a giant piece of metal turns it into a moon-shattering relativistic kill vehicle.
[/quote]

FTL tends not to be literally FTL in many space settings so I don't see the problem. Often which it just means you press a button that warps some space and pretend light light speed barrier doesn't exist until you pop back in real space somewhere you want to be.