That's why I'm confused why Urobuchi decided to write off Baron Lemon Energy. As unexpected as it was, it presented an opportunity to make Kaito an equal at least regarding Kachidoki. That would at least leave enough room for Overlord Baron vs Kiwami alone in order to have the Overlord battle as it is.
Due to couple of reasons, I suppose. He wanted to emphasize the fact that Ryouma just doesn't trust anyone, and is aware that the Genesis Drivers could be a bad thing if used against him. And thanks to that, Kaito eat a fruit. And I do believe that even with an upgraded GD, Ryouma would still lose against Kaito. Also, we don't need to see more of Lemon Energy Baron, we need more of Lord Baron. 4 episodes are not enough at all, while we barely saw Mango, compared to Lemon Energy. Also, I doubt Kaito would want to switch to the Genesis Driver. Because if he wanted, he COULD do it, as Yoko's driver was not destroyed (or was it? I think it wasn't), hence he could get her Genesis Core just like she got it from Ryouma's Driver.
Ignoring how you just insulted my intelligence with the sentence in bold, that only brings up another question: Why spare Earth? Clearly other dimensions were not able to fend off Helheim either, what makes Earth so different? Hell, why even force evolution on others anyway? There isn't even a "because I can" style statement. This is not even a nitpick, this is basic character motives. This series spends so much time on being "dark" and "the sad" yet when it comes to something that simple it is just "whoops!" *facepalm*
And unlike most people here I thought the series got better from 31 onward, stuff actually got done once Kikaider was brought in.
He didn't insult you. You don't have to jump on assumptions like those. He just said that you might have not learnt it or you just don't remember. We don't know the same stuff, so there's no reason to argue about what we know and what we don't.
Anyway, I'll solve your question. It's true that what Helheim/Sagara does is not anything to "because I can". It's rather a "I wanna feel like a God" thingy. Think of it. What's the point in destroying? Anyone can destroy, but who can actually make another species evolve? Someone with the power of a God. Someone who is clearly superior to everyone and anything. If you had the power to do so, why wouldn't you do it? Helheim is a forest, it can't drink coffee or watch the Champions League. So if it has a "body" which can represent it, it means it has self-consiousness, so it's only natural for it to search ways to get pleasure. And knowing that you invaded other worlds and forced species to evolve is quite an awesome achievement. After all, it's just like a TV show. You can see so many different species using so different ways in order to survive and finally evolve. It's not a game nor a toy, it's an amusent act. Something that makes Helheim feel the absolute greatness as a world. Also, there's the possibility that it wants to be inhabitted by other species, so if they always end up going extinct, or not even ending up choosing to live in her, it's only natural for her to go after other worlds.
What I'm wondering is, did it really evolved apes to humans? How? And why didn't people end up living in the forest?