There are some skills that have specific damage type as %inc damage on the + to skill affix. Example Firebrand (Fire) and Shatter Strike (Cold), while many others have just generic %inc spell damage, which feels much better, because a) it supports multii elemental builds way more and more importantly b) these skills have conversions which don’t match with the damage type their provide. Shatter Strike just got a new conversion, so I have the devs will remedy this, but some of the other skills have it for a long time already.
It really makes some of these affixes feel much better and much mroe worth it compared to others.
One thing were this is actually detrimental: Primordial Exalted Affixes. When the secondary damage bonus does not fit your build it is more likely or not a complete exclusion criterion for even considering this.
Sometimes when playing or theorycrafting builds it feels like a slap in the face, because one skill works perfectly fine while the other just don’t get any benefit, just because you choose a specific conversion.
So I hope we will get a pass on all + to skill level affixes and make their secondary stat always benefit the skill regardless of what conversion you choose to play.