The solution to this "support itemization" issue already exists -- Spellthief's Edge, Ancient Coin and Relic Shield.
Just drive up the gold generation of these items, but increase the penalty for last hitting lane minions while having them so that laners don't buy them AND last hit in lane. Making it work in such a way like "wielders get half the gold from minion kills within X seconds of using the Tribute/Favor/Spoils", while giving a huge spike to the passive gold generation (the +2 gold per 10 seconds part) and the power of Tribute/Favor/Spoils to get gold would just give supports enough gold to buy regular items and completely avoid the problem.
It would passively nerf utility supports, but they can be buffed back into relevance by just making them scale better off utility items. We already have the stat in the game to add to all the utility support items (and increase their cost) -- Heal and Shield Power. All the utility support items like Redemption would have even more heal and shield power than they currently do (but cost a lot more), and the utlity supports can use the greatly increased gold generation from their buffed Eye of the Oasis to afford them. Additionally, abilities whose utility scales off AP such as Nami's movement speed boosts could be changed to scale off of Heal and Shield Power.
Tank supports would build the Eye of the Equinox in an otherwise full tank build. Eye of the Equinox, boots, and all top lane tank items from there on out such as
.
Mage supports would build the Eye of the Watchers in an otherwise full mage build. Eye of the Watchers, boots, and all mid lane mage items from there on out such as
etc.