Having experimented with many of the different classes and their mastery options and being a long time PoE and Diablo player I’m curious…
Realistically, “passive” skills don’t exist within LE as far as I can tell. Holy Aura (Sentinel: Paladin) and Falcon (Rogue: Falconry) do have a passive effect for example but there are very few with any substantial impact or extended capabilities. I ask / suggest this as there are many players that prefer “lazy” or low “APM” builds which rely on few active skills, even going so far as to have merely one of them! Some builds of course are the exact opposite and have you using every skill as it comes off of cooldown in a specific order to be more efficient. To each their own of course.
Creating “passive” skills with their own related skill trees would not only support this style of play but it would also allow for an even broader variety of builds and enable for more customization of other active skills. Instead of having only 8 active skills based on level of class and then another 4 more based on points spent in that tree as well as the 4~5 additional skills that a mastery tree unlocks having a second category of skills that are “passive” instead of “active” would broaden out the builds immensely.
When building a warpath based void knight for example most of the play involves just using the warpath skill. A “hammerdin” build or “cap america” build mostly use a single skill as well. Many builds focus on a few skills and one or two of them are “filler” skills. These skills, which I would consider as non-primary skills frequently get ignored most of the time or have use cases which amount to a tiny percentage of the play time for the character. The existence of passive skills that could broaden the play styles of given skills, similar to how some legendary gear does, would be a more deterministic method of doing so without relying on the RNG or trading for example. shrug
Just an idea coming from a player with carpal tunnel that prefers the auto-chaining method of skills that you currently have for some skills and would love to see more planning and build out ideas that allow for less button mashing without decreasing build complexity.
Edit: I understand the developers goals of having a more “active” playstyle. I’m not suggesting the removal of that in the least. Many players love that style of play after all! I’m merely suggesting that broadening out the skillsets functionality to also support builds with fewer keystrokes won’t harm their game in the least. It will simply allow for a broader user base. After all, there are existing builds which do in fact rely on one or two keypresses currently, not to mention summoner builds, and these are clearly not following said guidelines of more “active” play. Using a “design decision” to justify not supporting fewer “APM” builds while fully supporting others is clearly something they’re trying to balance against supporting a broad player base. Otherwise they simply wouldn’t have summoner builds or warpath in their game, at all! 