Kind of recently, the drop rate for these cards in Vortex was murdered, although they are still supposedly obtainable with a very low chance both in Vortex and in high level dungeons.
I have ran these dungeons and vortex quite a lot of times, but i have never seen one drop for me or any of my team mates. I'm not saying it's impossible, but as it is now, these cards are pretty much unobtainable unless you're extremely lucky (naturally, their price has also skyrocketed).
I'm not a fan of these cards. In fact, I don't like them at all. There is no strategy in just filling your gear with them and maxing out your character's stats equally. But the reality is, without these cards your character will be very weak compared to the players who have them, since they can increase both their HP and their damage output at once. Running Lv85 dungeons is extremely hard since you will be one and two-hit by everything. The other choice is of course murdering your own attack by filling your gear with Stamina Cards, but that's not really the point.
The point is that right now we're left with a bunch of players with full All Stat IV in their whole gear, and the rest of the players who cant possibly get them at all, creating a huge gap between players who had the time to get them before the patch, and the newer ones. Even if you want to argue that these players have to get these All Stat cards again for their 85 gear, they are far better prepared to do so, than players who don't have access to them.
So, please, restore their drop rate in Vortex, high level dungeons are too tough to run without them!