With initial hype but failed promises, live service games have gotten a lack of trust from players due to poor performance. Therefore, is it worth investing?
Why not? Surely after some time, HD2 would be fun to replay, even if the content was the same as the last time. Not every game needs to be continually played forever, but games should be replayable forever. I still replay very linear games periodically even though I'm not seeing anything new, because I want to relive my memories of the game.
Another option is procedural generation, which would work really well for HD2. That's a pretty good stand-in for constantly evolving content.
The HD2 maps are procedurally generated so that they are not identical each time you play.
The overall storyline is set, but they craft how it plays out in response to community engagement, which isn't possible with random generation. We never would have had the mines vs orphans set up in random generation.
If it's self-hostable, it absolutely is. I self-host Minecraft on my home LAN and my kids can absolutely play even if the Internet goes out. That's by definition offline, though you can certainly put it on a public server if you choose.
No, you can't. They decided not to give you that functionality. But amateurs are able to get pirate MMO servers up just fine until the lawyers come through, so it's all possible for us to do if they let us.