We agree, actually. We are sending a hotfix very soon to add a chance for Librams of Resilence to drop from certain Blackrock Depths and Blackrock Spire bosses, and increase the liklihood you get Burning Essence from the Dark Coffer in Blackrock Depths. This should help make these items a bit more available, but still require the same process and ceremony to complete the arcanum.
I want to also take this opportunity to also clarify that the fire resistance numbers listed in the blog post are fully buffed. So that ~100 fire resistance breakpoint for Blistering/Heat 2 only requires you to have ~40 unbuffed if you have a shaman or paladin in your group. For many classes that is a single item and the new +20 Fire Resist cloak enchant from Hydraxian Waterlords reputation. For Molten/Heat 3 you’ll need to do a bit more prep and that is intended, but as alluded in my previous post, Heat 2 should be very approachable for almost anyone.