Anti-Taunt. No. That's just asking for an unstoppable Setup sweeper or wall. Or an unstoppable Baton Pass user. Anything with an ability to ignore Taunt would completely broken if it is allowed any setup moves at all.
Choice items are also restricting as penalty for the sheer power they help put out. Would I like to see more things with Klutz? Yes. Would I like to see something that can abuse Scarf or Band/Specs without penalty? No.
Well it's kind of the point of an ability that ignores Taunt, to have a a Pokemon that cannot be stopped by Taunt.
I get that you don't like the idea but unstoppable is a bit alarmist since I said nothing about such a Pokemon's stats or immunity to Roar/Whirlwind.
Along the same lines, a Pokemon or two than can use Choice items without penalty wouldn't necessarily be the end of the Pokeworld.
Clefable can get a 1.3x boost for free and we survive while Guts can already guarantee 1.5x with enough momentum to sweep before status wins.
Pokemon with very good abilities (eg. Poison Heal/Pure Power/Huge Power) are seldom extremely gifted statistically and in terms of movepool.
It's part of the balancing process. Nonetheless, their abilities can often give them a niche that other Pokemon cannot fill.