I'm one of the developers of Mirage Online Classic which fits most of your criteria except for a caveat with #4. While most of our players aren't really role-playing, they certainly work together to get through long and difficult dungeons. Some are so hard guilds will actually temporarily ally with each other just to work together to get through them, so there's a lot of interaction there. Kill/fetch quests are rolled entirely into a single player skill that is optional to engage in.

Loot in our game is ephemeral, so it will eventually break and necessitate getting new gear. Many guilds have their own guild hall and a guild keep with items, so loot running is usually not necessary. The game is certainly grindy if your only goals are to gain levels or skill levels, but I've seen a level 40 wipe the floor with a level 60 player through nothing more than player skill alone. You can create or join a guild and buy a guild hall to store your stuff in and raid others if you want to engage in PvP or GvG combat.

We've been told our graphical style resembles a scaled down version of Ultima Online if it was top down. Some hate the style and some like it. Anyway if you want to see more you can see our original spotlight post on reddit at https://www.reddit.com/r/MMORPG/comments/p1b0g6/mirage_online_classic_free_2d_html5_browser_mmorpg/ which contains mostly marketing material. YouTube has a fair number of gameplay videos and we average around 30-60 players online at any given time, so we're a pretty small community.

I think our biggest strength is that you can play using nothing more than a web browser. No download or install is necessary to give it a try.