Taric is really strong in places like Dominion.
He's more of a bruiser with solid utility than a straight up support now - if he builds tanky DPS you can't escape from him ever, and negating armor pen is brutal against pretty much every AD.
Usually with an item like Omen, just about any melee is almost invincible against any assassin or marksman in a 1v1. They can't stop a split-push and they can't get caught alone by you until Last Whisper or a massive disparity in gold/exp happens. Taric negating armor pen when it's actually grabbed (to his entire team no less) isn't a marginal benefit. You can also grab a fair bit of damage with armor, Sunfire Cape, Thornmail, and Iceborne Gauntlet pack a solid punch - more than enough to duel marksman and AD assassins and win.
As for his AD aura - I think you mean Sona's aura or Nami's AA ehnace is something only marksman want. Flat AD is something a wide range of bruisers and assassins have pretty solid synergy with. Champions like Zed, Riven, Garen, Kha'Zix, Lee Sin, and more benefit heavily from AD without needing to constantly auto-attack. A solid 65~70% of the fighters and assassins in the game favor AD as their damage stat, and otherwise committed AP champions like Akali, Katarina, and Malzahar can still get respectable syenrgy with AD in odd places.
Also, Taric himself benefits a solid deal from AD - when his cooldowns are running it's hammer time, and getting that CDR by pummeling foes in the face with 3070 AD and 525+ armor penetration. It synergizes increadibly well with his passive.
Alistar's 60~90 AD steroid largely pushes the same general play style. When cooldowns are running you still get to be a nusance by smashing faces in.