Sometimes i feel like Sighstone should not exist
I think the vision game should all be based on trinkets at this point. With some balancing and tuning you could do it.
The problem is that Riot wants the vision game to be pushed across all team members. This season however did the exact opposite in a sense. Where the vision is now more then ever focused on the support (sometimes jungler) because he will be the only dude FORCED to buy this damn item just to put out vision.
I'm okay with that since i play a lot of supp, but it's the exact opposite of what you want rito. Everyone should be useful on the vision game with their trinket. Get rid of sighstone.
It's not like anyone wants to buy it anyway for the stat or something. You are forced to buy it to have decent vision at objectives.
Then you find in solo queue people who wants to play supp but don't buy sighstone and then you lost lategame couse you see a black map. This would solve that problem too.
I'd say the yellow trinkets should work more like a sighstone, maybe gaining more charges as you level up more.