Hi there, this is something that came to mind as I was playing some Titan's Fist runs. I experimented with multiple builds and eventually found some success with a STR-based movement-attack build. High STR for damage and durability, bloodthirst to leverage healing from Aux Power's enhanced damage output, swiftness/mobility for a perfect combination of survivability and damage output, bloodlust for SP sustain, probably a build that a lot of people have done at some point, but I found it very suitable to the playstyle and so far has taken me deeper into the tower at a pretty quick pace (currently in front of Phoenix Sanctum with, funnily enough, 2 level 36 Thrones I found in an earlier sanctum).
However, something's also started to bother me about this playstyle. My character is running ghost pierce, 6 supporting passives, and the instant speed buff skill. My character has developed into just making one button as good as possible, and as a result I've found myself interacting far, far less with new demons and their offered abilities. If earlygame I was macguyver making the things I had work, now it's turned into a pretty binary experience of "does the demon either A) offer a better version of my button, or B) offer a better passive at improving my button than the ones I already have", which makes me care less about what I encounter as I dive. Granted I have other demons, and some do have a high ratio of active abilities, but those are specifically support demons: One has every buff I can find, rabblerouser, and panacea, the other has life transfer, compassion, panacea, regeneration, etc. I consider these the most important demons in my party (aside from the extremely powerful OOD thrones of course, because of their sheer strength). It occurs to me that although these demons have more active abilities, it's because their abilities are -also- all about making my one button better, either by keeping me alive and undebuffed or by boosting my damage/accuracy/etc. I can't help but wonder if for the rest of the game I will be killing all enemies with Ghost Pierce.
My point isn't to rant about movement-attack builds though, as I chose to build that way in the first place and clearly it's a known archetype that works as intended. When I started to see an issue is when I tried to do other builds, again physical damage as that's where I have existing familiarity. Once again I found myself gravitating toward one button: in this case an AoE like Cleave or Earth Break due to their relevance to 1vMultiple Titan Fist encounters. Bloodthirst, Bloodlust, and other passives are so good I simply find it difficult to justify taking other attacks, which don't benefit me unless I use them. An attack backed by a lot of passives is simply better than an attack backed by fewer, often even should it not be perfectly contextually appropriate. Even if in the AoE example I run out of SP and have to resort to basic attack, it does a relevant amount of damage, it costs no SP, it benefits of my physical passives with the additional benefit of +1 passive as it doesn't take a slot. Basic Attack might not be as good as Heavy Slash but Basic Attack+Parry is already starting to close that gap. In my opinion, when it comes to physical attackers and perhaps some categories of magic attackers, the opportunity cost of using a slot on additional attack skills just isn't worth it in most cases.
I think this is a shame, for physical especially, because there's so many various attacks in physical that become hard to use compared to just picking one + a ton of passives. Even if you're not building something specific, it's hard to justify against plain old HP gain (stone stance, parry, etc) when more attacks offer nothing more than sidegrades. For demons there's also the question of if they'll even use the attacks well. I do like passives, as they're what let you develop interesting synergy systems with characters, and a lot of them are already quite low impact. The thing is attack options are often even lower impact than 20% movespeed or 20% block against most attack elements. Essentially, it becomes an issue of why you'd pick a sidegrade over a strict upgrade.
With that in mind, how about some passives that directly incentivize having stuff other than passives, possibly even themed? Some rough examples:
Slash Expertise: If your last action was a slash attack, you have 10% defense for each slash skill you have.
Impact Expertise: Your impact attacks have 10% additional of their original chance to inflict status effects (including passive-granted chances) for each impact skill you have.
PIerce Expertise: Your pierce attacks deal 10% additional damage for each pierce skill you have.
This sort of mutual-exclusivity with other passives should mostly prevent it from becoming a strict powercreep of the existing passive pool and thus with the right values be pretty balance-unintrusive, but should significantly improve the viability of attack-diverse builds to help them compete as an option against single-button builds. Another nice thing about this sort of passive is it's very build-flexible, unlike passive-synergy chains which in my experience can become very rigid as they get more optimized, due to attacks themselves being sidegradey options you will have a lot of versatility in how you want to compose a set of say, 5 attack skills, one "expertise" skill and 2 other passives. There's potentially all sorts of stuff you can do with these build-contextual bonuses, but in this case I decided to just target-incentivize something I'd like to be more practical.