Apparently this is a old and painful issue dating back from before 2010 if I believe the posts here, but anyway it bugs me too that this hasn't been fixed in the mean time. Or am I mistaken?
I want to see the maximum value in graphs instead of the average for time periods. That is more meaningful data to me.
Honestly, it can't be that difficult to implement. One just adds min,max and avg values into the round robin database for each timeframe and lets the user make a choice which one(s) is(are) displayed in the graphs.