If you're trying to run someone down in a 2 v 2 during the charge up time, you can be swerved out of alignment by a minion and miss the stun completely. It's hard to predict when this will happen and it can drastically effect a skirmish if you cant get the stun.
I'm pretty sure Repertoire considered this when he worked on the Taric update. Lucian for instance gets it for his R for the same reason. I'm going to trust that we decided not to give him ghost during the E delay for good reason; I'd assume it's too much invisible power to add on something that can be used relatively frequently (it's not an ult). I'd be sad to see Taric use E while running away just to path through minions.
That'd be pretty dumb, all things considered. If he wants to stun me, he should have to put himself in a position to do it, not get a free pass through my defense wall of minions.
coming from a mastery lvl6 taric support main it would be nice but that's his only counterplay other than his small start on mana
I'm all up for buffs but this one is unnecessary and silly.
Edit: If we allow Taric to have this we might as well let every other champion with a similar issue have it as well.
coming from one of the top 1000 tarics in the world, this would be super helpful.
It is immensely annoying to try and do anything in lane because of minion block
Only if Zac gets to ignore unit collision when he's within 25 units of a blob and moving towards it.
Yes I know he's overtuned right now and obviously he should be nerfed as well, but I don't think it would be crazy to have less "No fuck you you don't get to pick up your blob that's right there"
I echo thoughts said by others that this would be too strong. 
is a much better solution if you want that.
Coming from a Taric one-trick (Currently Gold 5. Mastery lvl 7 on Taric) This is would be extremely helpful. However, while this would certainty feel good for the Taric player, it might remove the need for proper positioning with your stun, which is the thing that keeps the ability balanced in the first place.
Allow me to propose a similar buff for my main so you can see how much of a bad idea that is. Vi should be able to ignore unit collision while charging her Q.
