I think I finally have a handle on exactly what Goat Simulator is trying to be. You know how, in your typical open-world game, you'll have times when you're between missions, and for whatever reason, you're playing the game, but you don't actually want to advance the story at all, so you pick something at random in the environment and decide "I'm going to climb that" or "I'm going to explode that?"
Goat Simulator is a game made entirely of those moments. I can't exactly fault it for being that way. On paper, it seems like a good idea. People like messing around in open-worlds, so why not make a game that makes messing around the centerpiece activity?
I'm not sure why this idea doesn't work for me. I like sandbox games. I loved StarMade, even though it wasn't finished and there wasn't much of a goal, so I had to make my own objectives. So why am I so indifferent towards Goat Simulator?
I think it's because I don't have any particular investment Goat Simulator's world. I can't make permanent changes to it, and there are no interesting characters or stories. Even my player avatar, the Goat herself (you can become Queen of the Goats, so I'm assuming that makes you female) is really just an abstract player stand-in, so obviously absurd that any identification is smothered before it can develop.
All of this adds up to a faintly sterile experience, something that can be appreciated with a critical distance, but which never quite sets fire to the imagination. And if that seems like an awfully subjective assessment, I can't disagree. It's likely that I'm only speaking for myself, and that other people will have no problem getting into the game, having a ball with trying for ever more insane acrobatic feats or elaborate physics-modelling catastrophes. Hell, I've played this exact same game before, after beating Saints' Row IV and having nothing left to do but finish the "challenges." It's just that after 20+ hours with the Boss (not counting the previous games in the series), I'd felt a bond, thanks to all the funny dialogue and zany set-pieces of the main plot. With the Goat, all I can muster so far is a shrug.