Make Ruby sightstone increase you max number of wards from 3 to 4
This would make it actually have some reason to be bought before 50 minutes when you have all your other items built.
More wards means more map control.
More map control means more chances to see what the other team is doing.
Knowing what the other team is doing means more chances to exploit their mistakes.
More exploiting their mistakes means more gold
More gold means more damage and tank stats
More damage and tank stats means more likely to win team fights
More won team fights means changes to take objectives with little to no resistance.
So riot why not make ruby sightstone have some real value beyond just another ward charge and another 200 health?