+1. We are also running into this issue.
We need the ability to conditionally format a KPI metric measure. Depending on which KPI metric the user selects, we need to format it as dollar amounts, percentages, or an undecorated decimal numbers. We need to display this measure in heatmaps (looker_google_map). There is currently no way in Looker to do this without compromises.
By using html on the measure, we can format the value shown in the hover-over tooltips on the map, but the legend will show non-HTML values. By using value_format with conditionals, we can differentiate between dollar amounts and percents based on value magnitude, but there’s no way to handle undecorated decimal numbers.