Not every game needs an open world, D3 is fun the way it is, combat is extremely bloody, fast. Personally that's my favorite part i always get into it at least for few hours every week, also you not seeing it as fun doesn't mean others see it that way as well buy Diablo 3 account, crazy i know.
Asking what the point of playing this game is to ask why people raid Heroics in WoW and any end game content in any game. To get a good jump on new content on the next expac. Its a really silly Question OP. When new stuff comes out, Do you want to be 1 of them players that are broke and left out? No. I already have 14 billion saved for walking into the new expansion. Are you ready?
Don't think you got the question I asked why the people who grind 24/7 literally mainly streamers play when there's no money in the game like there use to be, I already know the game is fun I enjoy it myself and it's nothing like WoW so don't compare it to WoW.
I get the fun by setting goals in D3. In Hardcore that's easy: get every buy D3 items class to lvl 60 HC and kill Diablo in Inferno.
Others may set for grinding keys and constructing Hellfire Rings or create über avatars with über gear. Be that HC or SC cheap D3 gold.
The key word is "fun" and it is up to the player to find it in ANY game.
The last few days I also played with little cyclists to simulate the Tour de France or some cycling classics in a boardgame ...
I guess 99% of the people won't understand it, but the problem is that no one can define "fun" for each individual.
And Diablo 3 offers spades of fun for 3 million people per month apparently.
No need to try to counter this with useless posts.
D3 is there and liked by those who play it (be that from time to time or every week, day or monthly).