Compared to Rachel or Hayate? By a country mile. I also never implied that Hayabusa was "harder" anyway, just that he's on the opposite end of the spectrum on the Brain-Dead meter.
I wouldn't say Hayate is braindead. Just make sure you don't YOLO 3H+K all the time Joke aside, he definitely needs work in order to succeed with him. But he is one of the easier ninjas to learn imo.
^That's not the reason why Hayate is seen as braindead though. There's a lot of characters that can get much higher damage output from wall splats. Akira can easily get up to 100 pts of damage with his 3H+KP466P+K and he's far from braindead. It's because of Hayate's safety and the dumb 3H+K shenanigans that you see most online Hayates do.
Really? I have yet to see a Hayate go for Raijin online. And it is indeed an overrated throw. It's not even practical. Nakiryu is sufficient enough as it takes out 1/3 of their life on Hi-counter and is much easier to perform. Raijin's just for show.