Board Thread:General Discussion/@comment-7431551-20140405020542/@comment-6554265-20140405062231

Basically, because they're easily controllable, mass-produced, can launch undetectable nukes, have almost indestructible armor (from usual weapons), and are really the combination of super-mechs and nuke silos. Yeah, it's pretty impractical, but I think the main reason is because all you have to do is hop in the cockpit, and boosh, walking battle tank. Plus, it's really fast, mobile, and agile, as proven in the fight between RAY and REX, while other missile silos are stationary.