I’ll try to brief as I can, though probably not possible.
I don’t think D4 is a good ARPG and Im not saying this to say “d4bad”. I actually hate that meme. Im not trying to be disrespectful. However, the game has an identity crisis. ARPG or MMO?
I don’t even think it has many ARPG elements. Aside from a decent amount of loot dropping on the ground and the action combat of an ARPG, it doesn’t have a ton of other ARPG elements and those that it does it doesnt do those very well.
D4 has more themepark-MMO elements (similar to a Lost Ark) than it does ARPG. Open world, Open world bounties(whispers), Open world bosses, open world public events, timed thematic public events (helltides and seasonal which seems to be the sole focus of most seasonal content as of late), Raids, minimal skill tree, etc. I feel like Im bouncing from themepark attraction to themepark attraction. From Seasonal helltide(apparitions) to regular helltides to world boss to Pit/NM dungeons, and back to seasonal helltides. Just bouncing and bouncing on all the rides at the themepark.
Contrast to actual ARPGs: POE1 where youre sitting in your atlas mapping. Same system, same customizable endgame with the seasonal mechanic IN your maps (certain league exceptions noted). POE2, youre in your atlas mapping and customizing your endgame. Last Epoch, youre in your monolith customizing your endgame experience. These games have you in a singular endgame system that is far deeper and more customizable than Diablos, where in D4 you are bouncing from system to system like rides in an amusement park…
My suggestion to the D4 dev team: Put out a manifesto detailing what Diablo4 is and where you want it to go, and push the game into a more Lost-Ark style MMO ARPG. Not saying copy-pasta the gatekeeping toxicity of Lost Ark or any of the P2W elements. Heck no. But the game feels a lot more like Lost Ark than it does any of the other ARPGs on the market that do ARPGs well. MMOs by nature have a more shallow skill system and a lot less build customization, just like D4. Just like Lost Ark. All signs point to this. And with seasonal content…your seasonal content has been heavily weighted toward open world/public & shared experiences via Bloodtides (S2), Realmwalker (S6), Witch events (S7), Apparitions (S8) and if Im not mistaken the next league is a “powers” league so its likely the same thing. A lot of the game’s baseline content is open world and public…MMO.
That would be my suggestion.
tldr; Re-brand the game to “World of Diablo” (and actually put Diablo in the freaking game).
Lean more into the Open World / MMO style elements of the game, re-work some classes, builds and archetypes to lend itself to more of a trinity (I wouldnt make it required but make supports sought after for content), more raids (but really improve on the citadel concept), more MMO style stuff. Keep the Pit, Infernal Hordes, etc…you need some solo stuff. But go all-in on the MMO content you have. And put out a statement saying the game is moving away from being more of an ARPG and heading more toward MMO ARPG. This way, its not competing with the other ARPGs that execute the core pillars of ARPGs MUCH better.