I think you're larger point here stands-- Thanos is presented as someone who is supposed to be very intelligent in universe. The fact that we can pick apart his plans is largely a failing of the writers to properly convey that intelligence, which isn't shocking given that involved a whole host of different creators spanning almost a decade. It is impressive that the MCU hangs together as well as it does.
As such, we should probably treat Thanos as reasonably smart for rumbles purpose's and chalk the instances where he isn't as PIS.
Would Earth have actually lost though? Nukes seemed rather effective against the Chitauri. Now, if New York had been nuked, the Earth would be doing... not great in the aftermath. But I'm not sure that army would have subjugated the planet.In fact, when he sent Loki and the Chitauri to Earth - which does seem a bit absent minded on his part - the Avengers didn't actually exist. It looked like an incredibly easy task - and had the Avengers not come together, Earth would have lost the battle emphatically.
Not planning for Ronan to look under the hood and find out what he had seems like a pretty big failing. Especially when the level of security around the stone was basically nill. If he sent Proxima Midnight in instead of those Kree underlings Starlord would be dead and the Power Stone would be his.When he sent Ronan to get the Orb, he didn't know Ronan would find out it was an Infinity Stone. It looked like a straightforward, fail-proof plan, but when Ronan inadvertently discovered the true nature of the artefact, things changed.
Again, agreeing with your larger point, but I still don't buy the specific explanations for his previous screw ups. It is better, IMO, to just chalk it up to plot wholes/PIS than try too hard to justify them.Those are the times Thanos looked silly re: his plans. And they had unforeseen circumstances derailing them.
Every other time Thanos has tried to achieve something, he's succeeded.
We know he successfully predicted Titan's fate, we know he successfully decimated Xandar, we know he successfully decimated the Asgardian refugee vessell (half of those on board escaped - and I believe we'll find out Thanos allowed that to be the case), we know he successfully decimated Zen-Whoberi (Gamora's home planet), we know he successfully decimated the home planets of Nebula, Ebony Maw, Cull Obsidian, Corvus Glaive and Proxima Midnight (he took one orphan from each of their planets), and we know that he successfully got ALL SIX of the Infinity Stones when got serious, successfully overcoming everything the heroes threw at him. Moreover, over the years, he's managed to recruit entire races (Chitauri, Outriders) to be under his command, and he has countless large vessels and war machines at his disposal - none of that will have come easy. It would take someone shrewd.
He's clearly far from stupid.