Hideyoshi Nagachika is extremely important, very important, very much important yes. Hide was never one to be shy around people, at all, HE’S the one that asked Kaneki to be his friend in the first place. HE’S the one that was Kaneki’s voice half the time, he knew everything about his friend because of the countless time’s they spent together. I mean I guess you can say he also saved Kaneki.[his thoughts, btw]. Also, another simple reminder that Hide was still putting up missing posters for six months without hearing a single word from Kaneki, seeing as he always was looking out for him, there obviously was an idea in his head that his friend was still alive. Rather you go off the manga or the anime, both result into Hide being important. Do not forget that Kaneki went through hell, he was tortured and changed into a mosnter. The world soon drastically changed around him and the boy grew terrifed and drowned himself in this self loathing of being something that could really kill someone he grew up carying about – his only friend [not to mention various others that he learned to care about along the way] Kaneki was terrified of Hide knowing the truth about him T/T. In the end, Hide gave him what he needed; which was understanding and acceptance. Hide looked at him with no judgement, despite knowing what he was and the mistakes he made. Hide is someone that would wait for Kaneki when he said ‘just a moment’ to standing by his side when being told to leave him alone. Despite all that Kaneki went through, and despite everything that happened – Hide never changed, not at all. and That is why Hide is important.