What one needs to understand is that the technology in STAR WARS what thousands of years more time than ours head. Even though this is the case, the technology when it comes down to body/mind enhancing / body repairing isn't perfect and isn't something commonly done.
To make two canon references:
(1) General Grievous who once was a Kaleesh warlord. An attempted assassination failed and he survived but to save him, he had to be transformed into a cyborg. By cyborg do I mean, everything apart from his inner organs, he was a robot. Even though this greatly enhanced his skills (Just see the four arms with rotating hands), the engineers whilst working on him didn't do anything to enhance his mental power while they were on it.
(2) Darth Vader who once was a human got locked down in his suit with an half-cybernetic body which was - source is the book: "The rise of Darth Vader" - far from perfect, even though its discussed this was also sort of punishment from Darth Sidious for his failure to kill Obi-Wan Kenobi. Again, no one seem to have bordered to enhance Darth Vaders mind. Else he would not have described himself as a wreck and they could have done something about the pain he always feeled and all the problems he seems to have with his new armour. The droids placed implants, that helped him hear and see and feel. But no direct mind enhancement has been done either.
So, going out from a canon point of view, I do not see mental enhancement in form of a sugerical modification as common, I just think the risks involved in such a thing are too big.
