I mean admittedly the problem is they set it up to be this massive hype thing that couldn't be broken and was an effort to keep The Walkers out and had magics the dead couldn't pass - so how do you then convincingly write something that could take it down when they have no way of directly passing it, short of knocking it down... which would otherwise take fucking years.
I'd honestly say the Wight Dragon was the best thing they had, and given GRRM very likely told them "This is whats going to happen" they kinda had no choice on that.
Also; Aegon's Conquest when