Begin lengthy sarcastic vent in agreement with the OP. TL;DR at the bottom:
Sadly this free and benevolent gift from riot games (literally a GODSEND to supports after the warding changes) known as the trinket upgrade is a rare beast, seldom encountered outside high silver and up. The elusiveness of this creature can be directly attributed to the lack of awareness, as it's beauty and grandeur have a direct impact on the overall state of the game.
These creatures take upon many forms, each having a different remarkable ability, such as to conjure up mystical "wards"; areas of vision seen and unseen to the enemy, create zones null of sight and sound that allow the dispatch of said wards, and even amplification powers so potent as to allow it's user to see into the unknown, for a time.
As a rule, a team's overall awareness of it's power, and thus their chances of winning, are directly affected by the number of upgraded trinkets that team posesses. In the Bronze fields of justice, this creature is only seen once in a blue moon, maybe twice on a single team if lucky. The irony of this seemingly rare occurence is that after a champion hits level 9, they gain the ability to "purchase" this wild beast.
This creature can easily be lured and captured with 250 gold pieces. Given the extreme abundance of minions and neutral monsters who leave large piles of this substance around upon expiry, you would think that such a powerful being would be highly sought after, but only in the highest eschelons of League of Legends competition is this actually the case.
This irony stems from novice summoners taking for granted that the giants in the League Competitive Championships that we so often look up to rely not only on their extraordinary summoning skills, but also the fundamentals that we humble novices often fail to use every day. They routinely purchase trinket upgrades and the more specialized purchasers among them have even discovered such potent knowledge that they are able to transmute 800 or so gold pieces into a regenerating dispensary that draws upon the same power that trinkets of the vision variety do to dispense their wards. These dispensaries are known as "sightstones" and often have as great an impact on the vision of the team as 2-3 upgraded trinkets.
As the relative anonymity and thus rarity of this knowledge pushes the upgraded trinket closer and closer to extinction, we must strive to raise awareness of the methods of it's proliferation, and thus it's potential for survival. The most successful of these, if the least known, is the simple shop-ping captivity capture program.
Often a summoner gets carried away in the bravado of clearing minion waves, farming jungle, tower sieges, and slaying others' champions with their own champion, neglecting to remember the importance of vision in the fields of justice. The simple act of taking a leftover sum of gold to the shop to capture an upgraded trinket's can often go forgotten, and only when need of the trinket's power is dire do summoners then heed the call.
By then it is too late, and the time and effort required to fully utilize the trinket's gifts is wasted by lack of foresight and preparation. There exists as simple remedy to this, known as the shop-ping captivity capture program. By channeling your psychic energy, a summoner is able to press the ALT key and click another summoner's champion portrait, summoning a blue 'ping' at that champion's location. By following this ping with a telepathic message, even something as complicated as pressing ENTER and typing 'go upgrade your trinket while your lane's not pushed in scrub' and pressing ENTER again can convey an otherwise incomprehensible message to some summoners.
This simple process takes only 15-75 seconds to complete, but the impact it has on a game and the trinket environment in general often lasts 15-75 times that long. Together, we can bring upgraded trinkets back into the realm of popularity and out of this dangerous obscurity! Spread word about the Shop-ping captivity capture program today!
End Vent
==============================TL;DR================================
Seriously, it takes 250 gold to upgrade a trinket to it's full potential, usually doubling or tripling it's up-time and thus effectiveness. 250 gold is barely a whole minion wave, or two jungle camps, usually. There is NO reason why you would NOT want to upgrade your trinket as soon as possible, the trinket's effect on gameplay is HUGE and CANNOT be overstated. It doesn't even take up an item slot, IT HAS IT'S OWN. So there's NO EXCUSE NOT TO GET ONE, and an easy way to get it is just to farm one more wave or clear one more camp on your first back after level 9. BAM, you've got enough gold to upgrade it right then and there, along with that 
or 
you were saving for. If someone else on your team is level 11 and doesn't have an upgraded trinket, ping them and ask why. If they don't have a reason, DO NOT RELENT UNTIL THEY UPGRADE. Even then, remind people to ward/clear/scry by just saying 'need vision/sweep/scry' and pinging MIA pings where. This can often mean the difference between a good engage and a lost teamfight, and I see people with a grand total of 5 wards placed/swept/etc far too often in 40 minute games for there to be a valid excuse.
P.S. : To the OP, why the heck is this in gameplay and balance anyway? I appreciate the PSA and it's visibility, but G&B is more for champion gameplay and game mechanics AS IT RELATES to balance, not gameplay in general. Would this have gotten better reception in General Discussion?
