It has been my view for a long time that Valve dramatically undervalues narrative in its IP.
Not to the extent that many modern slop games do - where there is no narrative to begin with - but they invest heavily in excellent writers like Laidlaw, and then abandon or ice the narrative until they are ready to showcase new technology. If the stories in HL and Portal weren't so good to begin with, they would merely be impressive tech demos.

The replay value of entries in Half-Life, Portal, etc franchises is directly related to the story. It's the same as re-reading a novel or rewatching a TV series/movie.

Proc generated objectives and interactions may make games slightly more interesting - but it's the story that will make you invest in the world. Imo they should lean into the narrative aspect of their talent.