Size Standardization
Players have trouble intuitively understanding the cost of a unit. This often crops up in balance- players expect larger units to be more powerful and cost more, and smaller units to be less powerful and cost less. They may be surprised to discover that, for example, the black dawn and sniper both cost in the range of 1k, despite being around the same size as a zeus or rapier, respectively.
Within the game world, given that unit mass is based on metal, it also makes sense for units (unless they are hollow or underground, say m storage or pop-ups) to reflect their metal cost in their size.
A different standard may have to be applied to buildings, however. For example, i do not think that a mex can seriously be made to be smaller than a peewee.
There is also some question over how to establish a units size. Hitsphere for a square tank can be relatively accurate as to its size, for a tall, thin peewee or sniper though, the hitsphere is usually mostly empty. Hitboxes might make this slightly easier.
If you want to vote an option that isnt here, ADD IT.
