Look at the patch 1.1.1 and scroll all the way down to the bottom. There it says that the nerfs were not intended to affect the mythoclast and they are working on fixing it.

I understand that it wasn't intended but I don't get why it wasn't intended. It says it was nerfed because it is treated as a secondary or in other words it was nerfed because the system treated it as a fusion rifle which it is when the patch was added. The patch was supposed to affect fusion rifles and it is a fusion rifle no matter whether it's primary or secondary. I can only assume the patch is designed to alter the stats of all guns in the same category the same way such as all fusion rifles being affected so they have to separate the vex somehow in order to keep the current state of the other rifles which may be giving them issues as otherwise I would say it should be an easy fix.

The problem is that the vex is very different. I can explain it in the long, drawn out and precise way, however I have done this over a dozen times in replies to this post. Because a moderator changed the post(moved it to feedback) I can no longer edit the original post. Instead, I will give you the short version. The problem is how it fires, the mythoclast fires a single shot of a fusion rifle's usual five to seven projectiles per "shot". The nerf to fusion rifles that still negatively affects the vex was a cone increase, meaning that the "cone", or spread, on the projectiles is larger than it was pre-nerf. This works for normal fusion rifles, they have many bullets and only one kick per "shot". However, the mythoclast only fires one projectile at a time, and kicks for every single one. That means that, when affected by the nerf, it now no longer shoots where the reticule is pointed (in a random fashion, due to the cone increase), but also kicks off that point vastly more than other fusion rifles, making it extremely inaccurate. Top this off with the fact that all fusion rifles have a travel time for projectiles, and this cone increase nerf destroys the effectiveness of the Vex. Sorry, I ended up going with a middle-long explanation. Hope this answers your question! Also, as to why they haven't fixed it yet, I can only assume, for a reason perhaps similar to the one you described, that it has proven more difficult for them to fix than hoped. Otherwise, the only reason for it to not be fixed would be because they don't care. I sincerely hope this is not the case, but seeing how 1.1.1 is eight months old now and we haven't heard anything about it, I begin to wonder...

I didn't think about the issue of it being single shot. Makes sense that it should be separated from the fusion nerf. It's possible they plan to fix it with the TTK release.