Nik and others may correct me on this, but I believe that the guideline for which units are massive in FWC reads as follows:
"Vehicle units are considered to be 'massive' in Future War Commander to the degree in which such a definition would support and not violate the Rule of Cool."
For a further discussion of the Rule of Cool and its ramifications, please go to:
[i]But it's tough to really care about questions like, "Why did that happen?" or even "What's going on?" when you're constantly interrupted by "Oh my goodness! Giant robots! Wheeee!"
— Peter Suderman, reviewing the 2007 film adaptation of Transformers
"The laws of physics must be out to lunch."
"They're too busy watching." [/i]