Well maybe not childish but the Goldie and Shun event, Tenma flee with the donkey/horse is not something I am used to (compared to the original manga) but anyway.
As EndlessChaos said, he is not putting original materials in the manga. Cain/Abel vs Ikki!, Suikyo (Gemini Saga of Hades), Kaiser Light Punches, Tenma thought highly of Kaiser, Shun is struggling with soldiers and Tenma even though by the end of the original manga he is way stronger. Aldebaran's deaths....etc
Even the design of the Gold Saints, it's almost the same, Shion,Cain,Abel clones but without the huge hair tail, Aldebaran, Asmita only color, Kaiser and Aiolia. Even the same techniques -_-
While Lost Canvas, there are many great original ideas, design, attacks, same thing can be said for Episode G.
Also lately Saint Seiya Omega, they are at least trying to be different. What I want to say I had higher expectations from Kurumada in his new manga. Let's hope things get changed.
Cain/Abel vs Ikki hasn't gone the same as past Gemini battles, and it seems things will really end differently with both Gemini appearing at the same time. And how is Suikyo Saga? He has different motivations (loyalty to Athena for a plan vs trying to save Suisho's soul), different results in battle (Suikyou beat Shion, Saga never fought Mu. Aldebaran died to a lower specter, Ox fought Suikyou in a violent battle, and damaged a Judge's surplice before dying. Saga easily forced his way through Gemini once he figured out the trick, Suikyou was getting badly beaten for a while there, until he was forced to leave. No Cancer Gold Saint vs a rather rough battle against Cancer Deathtoll in which Tenma ended up saving him due to cunning, and no Leo Battle vs one that ended with Suikyou's defeat). The only thing Suikyou and Saga have in common is a Sanctuary assault and being perceived as villains. For Kaiser light punches, you'll have to clarify that, I don't know what you mean. And so Tenma thought highly of Kaiser, if you're saying that's a reference to Seiya vs Aiolia, it's not. Seiya was mad that Aiolia was seemingly turning back against Athena after siding with him, that's not the same at all. As for Shun's struggles, you need to remember something important...THEY'RE IN THE PAST. Time traveling, remember? If Shun just went around killing people without a care in the world, this would end badly for the future. He was told by Chronus not interfere with the past while doing this mission. And Ox died with dignity, fighting a judge (not even Hasgard had that honor). Aldebaran died to a scent, it's a big difference. Besides, this Holy War ends with two survivors, remember? People have to die.
As for designs, Shion existed in the original manga, did you think he was going to look all that different then? Just with shorter hair. Ox is far taller than Aldebaran, an utter giant, and died to a much more powerful foe due to his cockiness. And what about Asmita? Shijima was the silent man (a different result that blindness), and has taken quite a different role in his life from Shaka, almost dying. And Kaiser? He looks similar, but we don't know a lot about his character (other than that he keeps an awesome armored pet lion around, which is quite original for the series). You're missing all of the original designs of this group (not counting Shion and Dohko since they were in the original manga). Pisces Cardinale, Capricorn Izo, Cancer Deathtoll (really varies there), not even counting all the original characters we've seen (new armies, got a spotlight on a new Specter, a new Silver Saint who became a Judge, new gods, etc). The Specters are always reborn, so they should share some modest similarities in the looks department.
And of course the other series had original designs, different art styles do that. And different attacks isn't always a good thing (think Zodiac Exclamation). Plus, Shiori repeated several of Kuru's ideas in LC, even if they failed, made little sense to be there, or if they did have some use (like Athena's blood to free Hades' host, Gold Blood in Cloths, God Cloth for Pegasus to fight Hades, randomly bringing in the Blue Warriors from that one short story, the whole Poseidon bit to reference a line Poseidon gave in the original series, Superdimensional space killing a foe for you, Balron judging sins *even though he was just taking over for one of the judges in the original*, the flying boat Kuru drew in random artworks, etc). Not saying she didn't do original work, but she couldn't resist referencing (like randomly letting Aiacos live, and telling him to go back to his name Suikyou). And, like with the Zodiac Exclamation comment, some of her ideas weren't exactly what I would call the best (The whole Leo Regulus becoming a zen god thing was just ridiculous, and all the god blood creating super warriors stuff too).
Omega has gotten better, but a lot of it's differences are iffy for me. Still, new Saint Seiya is good.
I just think you're looking at this all wrong. You're seeing all the similarities, but ignoring all the differences. A lot of issues with the time travel, the future events. If Ikki and co just went around killing everyone, it could fuck up time badly. So, they need to be more cautious, save who they can, and get Athena back. If she can return to her full body, then they can fix the troubles with the past, get back, and we can go on and assault Olympus.