Unbalanced Trinkets
I feel like the free yellow trinket ward is simply way better than the blue and red trinkets.
If you compare the blue and yellow trinkets, the blue trinket is nothing more than a 1 second ward that can be cast at a far range while the yellow is a close range 60 second ward. You could potentially use the blue trinket 1 second too soon to miss spotting the enemy team at baron while a yellow trinket ward is 60 times less prone to having the same effect.
Additionally, I can see the red trinket being useful in a lane verse champions like nidalee, teemo, caitlyn, etc. However I see little other use than that since you can't even clear a ward with them without good attack speed.
My suggestion is to optimize red trinkets for junglers and supports, so they can clear wards and traps to help get a gank off. The yellow trinkets are good for top and bot to ward lane, and I think the blue trinkets would be better if the duration or range was increased, or cooldown was reduced. Because right now it sounds like a really bad version of CV summoner which was hardly used back in the day.