It is important that the development team fully understands the mechanism for weapon calculation, and the fact that the algorithm has been referred to as buggy in several patch notes makes me doubt that they do. The new mechanism that you listed in the original post effectively does away with what Nubtro listed as step 4 in the quote below:
1. base weapon damage (base range of white weapons)
2. add +minimum (weapon) damage
3. add +min damage from Ruby
4. game checks if min damage is higher than base max damage:
YES -> use the new min damage +1 as base max damage
NO -> use original base max damage
5. add +maximum weapon damage
6. add +max damage from Ruby
7. multiply results 3. and 5. by "+x% damage"
8. add total min damage from jewelry and off hand (mojo/source) to min damage and total max damage from jewelry and off hand (mojo/source) to max damage
9. add "adds x% to elemental damage" by multiplying the min damage value by the x% and max damage value by the x% to get +min-max elemental damage
10. add "+min-max elemental damage"
However, I think what many people are ignoring, possibly even the developers, is that this step is necessary in order to prevent the minimum damage from exceeding the maximum damage. Whoever coded this in the first place probably had that logic in mind. Naturally, this isn't a possibility with any ruby, as they guarantee an identical amount of minimum damage and maximum damage being added, but other damage bonuses are random, so this condition cannot always be guaranteed.
By setting the base maximum damage to equal the minimum damage+1, the condition of the maximum damage being greater than the minimum damage is always enforced. Of course, it also ends up having the side effect of inflating the maximum damage by effectively double-counting minimum damage affixes.
The steps themselves are sound, all of the problems lie in the ordering.
If you consider this inflation of the maximum damage as buggy, then step 4 could be moved to the very end. You could calculate minimum damage with all modifiers, then calculate maximum damage with all modifiers, and if the final maximum damage exceeds the final minimum damage, then set the maximum damage = minimum damage+1. It's up to the game designers to determine whether that's desirable or not, but at this point in time, this method has indeed been used for such a long time that changing it would be quite disruptive, as you folks have indicated several times.
As long as it is consistently applied, it isn't a very big issue. The problem is that it's not applied consistently in the case of elemental weapons.
The real reason that elemental weapons are much weaker than "black" ones, is because the elemental damage affixes are added as a final step. If the elemental damage addition was done along with the plain +minimum and +maximum damage additions, this problem wouldn't exist, and elemental weapons would reap the same benefits as black ones from +% damage modifiers on both weapons and jewelry. This, of course, would buff elemental weapons heavily and would also likely be too disruptive of a change to actually be put in place.
What bothers me about this ruby change is that it now makes rubies inconsistent with black damage as well. It would have been more consistent to leave rubies calculated as they are now, and to adjust their bonuses downward, rather than have them calculated in a different manner from black affixes and adjust their bonuses upwards to compensate.