For the 6 endpoints that use the {wiki} parameter, there should be a way to get data for all wikis. I am hoping there is a way and it is just not clear in the documentation, but I tried using all, any, global, total, *, etc. in this parameter to no avail. I think any of these, or just allowing the user to omit the parameter, would be a reasonable way to get the cumulative total across all wikis. While it can be useful to have a breakdown per wiki, I would argue that for metrics, having a top-line stat of all views is actually more important than the stats for any individual wiki. And if there is not an API way to get the cumulative total, the only other way I can see to do it would be to get the list of all wiki codes and do the 200+ queries to check them all and add the results up—not very user-friendly!
As an example, I would like to be able to successfully perform a query such as this: