For some purposes, maybe. However, the story here is simply whether/when the price goes up and down. For that a normal scale suffices. It's also more accessible to the average reader.
Source: I present data and charts to a variety of audiences for a living
Because a change from $1 to $5 USD/btc is much larger than a change from $101 to $105 USD/btc. They needed two plots to show activity at two different orders of magnitude - that's the symptom. One plot with a logarithmic y axis would probably be a much better visualization.
You can't withdraw USD from Mt. Gox, so people buy bitcoin to withdraw, driving the price up. Incidentally the same site did an analysis on that a few months ago as well:
