I largly agree with or have no opinion on your suggestions but have a few things to add.
1) seasonal expierience
i feel like one month is a bit short. in diablo 3 i need one week to finish a season.
it just feels way to easy and thus unachieving. in diablo 4 i would prefer a longer strength curve.
if you are able to put an end build together within lets say 100h of playing i think its to easy.
one can define the seasonal goals so that an end build is not required. but in diablo 3 what really demotivated me
was beeing able to reskill all the time so there was no need to ever restart with a character except changing the name
and having all the items that i want within 20-40h playtime. farming for better versions of an item is unrewarding.
so i would vote for a season period of 2-4month and a longer progression within it.
i really disliked the multiplication effects of item. this destroyed all choices for how to put a build together. if there are items that double the skill damage the player is forced to use the item if he wants to use that skill. i liked the gameplay changing effects of golden items like "no cooldown" or "triggers ..." or "adds freeze" .. but the damage huge multiplication destroyed every bit of choice.
in my opinion the tier of an item should not be a game changing factor. this will lead to a boring farming for the same item.
since the team wants to make crafting more important why not drop "golden parts" that add traids when crafted into golden items.
if the player can combine them freely and also can find/buy different item bases like sword shaft/blade materials, it opens a
huge choice for custom unique items that can be customized to ones build. espeacially if one adds runewords to it.
i would like to see as much realism as possible. i really liked the lighting, but the character wasnt much effected by it. the area around the player is always lid up, this takes away from the dark athmosphere. there should not be an omni present lightsource walking with the player. if its to dark you can add torches to carry or light spell scrolls. when you stand next to a fire in the village every npc has a strong shadow on his back. but the player is lid as fuck. this takes away the feeling of beeing part of the world. it was in diablo 1 and 2 that the 2D player graphic fitted perfectly into the world. to achiev this in 3D graphic you need handle the player like everything else in the game.
also the player idle could change depending on the environment and status. having the player idle holding the club heavily breathing for minutes after the fight feels unrealtic. have the player graphic relax when not in a fight, or sit down. let them become a part of the world to make the player feel like he is.
i wish corpses wouldnt immediatly vanish. at least have them lying for some time. they can even have an effect on the gameplay. slowed when walking over corpses or less effective dash. wheather and environment effects should also impact attack animations and gameplay whenever it is realistic.
give projectiles a realistic speed. it will be hard to avoid arrows than, but it will force us to fight more strategic and ultimatly creating a more complex gameplay.
make the death individual to the death cause, dynamic mutilation woud really add to the game. especially for player deaths and pvp. execution animations spice up pvp and makes the player feel more human in the game. getting once head choped of by another player or a skelleton makes the world much more horror. gory like in "for honor" but based on the attack type and much less flashy.
get rid of it. its an abomination. lvl 100, make it unreachable.
a game with so much love from its community needs to get a lot of love from the developers. dont write of an idea because its to time costly, put every bit of detail into the game.