These people even without their doujutsu are able to master all kinds of jutsu with ease, which is why they have the title genius. It's not that their eyes is their power, but it is a tool used to help them gain that power.
Neji was labeled a genius because he was able to replicate super complicated jutsus that even some of the advanced hyuuga in the main branch could do, through observation alone and was able to master the chakra control, and to a certain extent, the gentle fist very quickly, becoming very proficient with it at a young age. His byakugan allowed him to see how the jutsus worked so that he could replicate it. It didn't do it for him.
Sasuke was labeled a genius because he was able to utilize elemental jutsu at a young age and was able to hold his own in taijutsu against opponents of higher rank than himself. His proficiency with sharingan allowed him to see ninjutsu and taijutsu techniques and how they worked. He himself had to work to actually use those jutsus, not his sharingan.
I don't see the problem here. These two are born with an ability/tool that helps them understand jutsus more so than others, but that doesn't mean that it automatically gives it to them. They had to actually work at it in order for them to use it.
Hardly .... If anything the only genius out of naruto's generation is naruto.
It is because their eye's ability that they are able to do so which is why it's stated "Their born a genius" meaning he was born with sharingan, meaning he's already a genius because he allows the user of it to posses great jutsu.
You said "sharingan allowed him to see ninjutsu and taijutsu techniques and how they worked. He himself had to work to actually use those jutsus, not his sharingan."
it's because he has a sharingan that he can see hand signs and follow people's movement's it's like obito couldn't do anything and as soon as he awakened his sharingan he was able to see his opponent. I agree with you to an extent although the fact is that he is granted massive advantages in battle and being able to see stuff which allows him to potentially progress faster but it's only because of his sharingan that he is able, which bring us back to " He was born a genius" Same goes for Neji.
Neji is good, better than most i agree but like i said before his entire fighting style is based around his eye which is another massive advantage when fighting against people. This is my point, i know it's their power and i'm not hating i'm saying that their called genius because they have those abilities that other's don't.
You can't argue with that because it's a fact and simple logic. however, i must laugh at the fact that Naruto was able to gain on sasuke that fast considering he was at a massive disadvantage. i know that the demon fox helped him but it didn't help in, in the aspect of obtaining jutsu..
The only Geniuses in my eye's that we have seen in the manga are... Kakashi, Minato, shikamaru and his dad. People who don't reply on jutsu ... Well kakashi does use his Sharingan but more his brain which is why he was one of the youngest Jonin in the village.