Vision Score Could Use a Change
The reason is that players can spam wards blindly in areas that don't really need them and gain a MASSIVE vision score.
It is important players use their wards WISELY so as not to place them on a near indefinite cooldown. Players should be placing them in brushes where they think the enemy might be, but only when they do not know where said enemy might be.
If you've vision on all the enemies and the enemy jungle is nowhere near your lane then you don't need to ward until after you lose vision on the enemy jungle, for instance.
Tactical warding is vital for surviving ganks from any source and for securing buffs and objectives.
But vision score does not take this into account. It only counts how many wards you've placed in addition to how many you've destroyed.
I think vision score should be changed from wards placed/destroyed to number of hidden enemy units revealed and how long you revealed them with your vision items including wards and sweepers.
This could encourage tactical warding for better grades instead of ward spam as the current automated system seems to demand.