I'm not sure why people keep getting upset about most of the Super Mutants being stupid? I thought that was the major plot point and problem in the first Fallout (that the Master couldn't produce enough intelligent Super Mutants). Correct me if I am wrong.
At least those didn't dress like savages. They were actually pretty high-tech, especially the intelligent ones, which were rigged from top to bottom in tech. The new ones just reek of orcs. But eh, I've heard they're from a different puddle of FEV (but then again, how did that get there??), so it's more or less ok.
And they
are pretty much dumber than the FO1 mutants. These ones just piss malice and decorate their outposts with skeletons and bodyparts (Behemoth even has a SKULL AMULET). Once deprived of a Master, the FO1/2 mutants founded a town (Broken Hills), so they were at least a bit civilized compared to these nomadic human eaters.
Fire sword is implausible but mini chainsaw knife is ok?
How's a ripper implausible at all? It's just a smaller, energy cell powered chainsaw. The problem with the firesword is that it's gasoline based (well, in the game, it actually just runs on magic, but you use a motorcycle gas tank to build it, so it's most likely supposed to be fuel powered), so a) You're using a resource the war was about, b) The gasoline would drip from the sword onto your arm and burn you. I wouldn't say it's that much about plausibility as it is about usability, you could probably construct something like this, but you'd also probably kill yourself in the process of using it.
The wasteland looks too much like a boring wasteland?
Personally, I think it looks too much like Morrowind, way too many boulders, it looks like a gravel pit. I can't really complain about it being "boring", it's not supposed to be exciting, although it is a bit repetetive (wouldn't stick out so much if it wasn't for the samey highway segments everywhere).