Having variables for dashboards so the queries in the dashboards change based on the varibale input. With filters, the query runs everything and then the filter is applied on top of it. With variables, we'd just be querying based on the variables.
Additionally, there are limitations with filters. For example, I want to have a variable for a situation like similar to:
'where keyword like '%{{variable}}% then 'Segment_1'.
You can't do this with filters to my knowledge.
Variables seem to be the one big feature missing from this product. This should also support mechanisms like dynamically selecting dimensions in charts.