They should bring back this:
However, quoted from there: "...as Blizzard felt that it was too much effort re-working every runestone as they re-worked every skill. So instead, they decided to remove them completely until they felt that their skills for each class were closer to being completed."
However, i have one suggestion:
To start off, Blizzard must remove all runes from the current skill system, and brings back the previous socketed skill system from beta. Players will then have to hunt runestones (Alabaster, Crimson, Golden, Indigo and Obsidian) which are dropped from monsters (rarity should be slightly better than legendaries), and runestone should be BoA). Players are able to hunt multiple runestones of the same type since players might need to use same runestone on different skills.
Instead of a total of 7 tiers from each gem possible, there will be only 1 tier only (more easier to code). Each runestone, once equipped to a skill, it will be the effect of the current runes in the game, ie. equipping Alabaster to Fist of Thunder will allow user to use Thunderclap, equipping Obsidian to FOT will allows user to use bounding light etc.
On top of that, allow different runestones to be fused or combined (whatever u want to call it) via a new or existing NPC, with gold. The number of runestones to be fused might be 2 to 3 (or maybe 2-5?). The effect of the fusion of runestone will be eg. fuse Alabaster and Crimson together, and the resulting runestone (Blizzard must create new names for the fused runestone) will have maybe 50% more effect from the first skill rune and 50% less effect from the 2nd skill rune, or vice versa.
Player fused Alabaster and Crimson and got Alabason (crap name i know, this is just an example). With the name implies, Alabason will have +50% more effect from Alabaster and 50% less effect from Crimson. So if player equip Alason to FOT, it will retain all thunderclap capabilties, on top of that, the damage is 50% more (52% dmg for the AOE), and it has 8% chance to dodge (50% less efect from Crimson, which is from Lightning flash).
Scenerio 2: Player fused Alabaster and Crimson and got Crimbaster. when equip to FOT, it will have 24% dodge, and 17% AOE damage.
If 3 runestones are combined, The stats may be 150% , 50%, 35%. 4 runestones may be 150%, 50% 35% 10%. 5 runestones may be 150%, 50%, 35%, 10%, 5%. The actual % to be determined, and the fusion results are RNG, meaning player cannot decide which runestone to tap 150% or which runestone to tap 10% during the fusion.
With this concept, players can only use the skills runes with the runestones they have, and with fusion, create skill build diversity. And since runestones are very rare and required hunting, swapping runestones during battles or not in town will not reset NV.
My 2 cents.