A planned economy under direct democracy would be at least as bad as a planned economy under a representative democracy because the average voter has even less knowledge about economics and business than a government planner.
The best thing about direct democracy is that, unlike representative democracy, we don't have it and therefore cannot instantly think of its flaws.
The average person reads under a sixth grade level, cannot perform long division, and quite possibly couldn't tell you how many years have passed since Jesus was born.
Whether a direct vote is appropriate for an issue depends on which is a greater danger: the corruption of a politician, or the ignorance and flakiness of the average voter.