This seems very basic and important. When sharing reports around with 8 decimal figures after the comma of dot, it looks silly and takes a lot of space in the dashboard screen.
How is this still a thing? This should be the easiest change ever. So simple. Yet so annoying to see decimal points when you don't need to on Dashboards.
For my own use case of averaging a grouped property field:
I was able to fix this problem by formatting the property to zero decimal points (Property format = "Formatted Number"). It may also work with 2 decimal point formatting--I haven't tried it.