While contributors have always been a big part of what makes his music great, I don't think he needs musicians better than him per se to make it great. I think it is fair to say that Gavin Harrison has been the only member of Porcupine Tree that would be called technically proficient (relative to his peers) on his instrument of choice, yet Porcupine Tree was awesome when it was Wilson, Chris Maitland, Richard Barbieri and Colin Edwin. Yes, the contributions of all have helped make PT what it was and is, but the awesomeness of Richard Barbieri, whom I would call Wilson's greatest contributor/band member ever, is proof that you don't need to be a players' player to excel when it comes to working with Wilson, as he is more of a textures and sounds guy than a player, but he always does such an awesome job.
When it comes to guitar, Wilson is more than good enough to carry the load on any of his albums in that regard. He might not be a technical wizard like Guthrie Govan, whose contributions to The Raven and HCE were definitely great, but his playing is fantastic. I am not saying he is David Gilmour, but like Gilmour, Wilson is living proof that you can crush it on the guitar despite not playing as many notes as possible.