I disagree that it was grounded before they had sufficient data. They had extensive video evidence of the fire and debris on the runway. The grounding occurred a few days after the accident.

Within a few days, officials will have significantly more evidence about what happened on the Ethiopian flight. Any decision to ground will be made based on that data, and any correlations with the data from the Lion Air investigation. It will not be made out of fear or speculation. It will be made by technical experts based on actual data.