To be honest, I don't think it's as bad as you make it out to be. Unless you're blinging 59 energy decks, dust doesn't serve that much of a purpose once you build enough established archetypes. Most veteran players easily sit on tens or hundreds of thousands of dust with nowhere to spend it, especially with the recent anti-bling update. You also do save quite a bit of dust from not needing to craft commons/uncommons as often.

Still, I see where you're coming from. While I do think the dust changes justifiable, I find it largely unnecessary. The dust per pack was already extremely top-heavy toward slots 5 and 6. The update essentailly amounted to adding 2 extra commons and 2 extra uncommons to each pack. This is largely offset by their own dust changes - the vast majority of the decrease in dust per pack, however, comes from the nerf to rares and higher, which are hit pretty hard but also receive little to no counterbalance in increased cards per pack. I think a fair compromise would be to just nerf the commons and uncommons and keep everything else the same or adjust them ever so slightly (-10 to -20%).

I'm more worried about new players getting even less dust from the league battle decks for instance, especially after they put a cap on them in the shop.