Sorry for trying to get back on topic, I just wanted to point out that the slideshows are only the technical aspect of an ending, obviously the content is what matters and unreal engine games tend to use these 'in-game cinematics', iirc. So it's not about 'sliedshows' per se.
Also I can't argue the good-bad-happy-sad angle - even though what the space kid says is indeed ridiculous - I only saw the stuff on youtube, but anyway I don't think it matters that much. (i.e. to warrant like 4 threads on an Obsidian board, srsly)
Still, the reason it fails imho is because through 2 (or 3) whole game basically you decided 'who lives and dies'. It was reinforced with game mechanics, the imported save games, missing npc-s, all this stuff was in the game, it wasn't all just ads and PR. And the end contradicts this mechanic.