What is the proposed idea/solution?
Many times your summary bar won't give the "bottom line" of a field that the user is actually after.
It only allows the very basics like "Sum", and "Average" but misses a universe of options the user needs.
For instance, it can not even give a weighted average by taking into account the values of another field.
Adding the option (see below) to customize a view's field summary metric (with a basic formula), will turn your database much more useful. Without being able to give things like a weighted average or calculate anything involving another field makes the ability of your database to give insights quite poor.
This will solve that:
customizing will allow me to name the metric I'm after, and use a formula to determine what is shows.