What are the limitations of the ecological footprint model and how can ecologists best use it?

The term "ecological footprint" has become very common these days when referring to the environment. Basically, it means the effect on the environment of one's daily activities. For example, recycling food packaging, taking the bus or a bike to work. The limitations of the footprint and reducing it is that on a personal scale we can make changes easily, whereas large corporations may still continue with unwise practices and cancel out the personal measures taken.