Are the lessons Pip learns during his journey necessary for him to arrive at the wisdom he evinces as the middle-aged narrator of this tale?
You have correctly identified a major stylistic issue within this novel. The narration is technically identified as first person retrospective, which means it is told in the first person and rather than being the person narrating the events as they happen, he or she is looking back and offering often wry or ironic criticism of his or her actions. This is a style of narration that is adopted in other novels such as Jane Eyre.
Your question seems to be related to a much larger issue that is crucial to the novel as a whole - is it better to remain ignorant and happy or wise but have to suffer? Certainly the wisdom that the narrator demonstrates has only come through the sufferings and trials that the younger Pip experiences - there is a definite sense that this is a novel of maturing, of change and growth in character. The incident where Pip saves Miss Havisham from being burnt and also burns himself in the process, and his loss of his "expectations" and the fever that cripples him have a sense of purgatorial repayment for the wrongs that Pip has committed - he learns just how much of a snob he has been, and how he has hurt others through his actions, and begins to right his wrongs. Thus we see at the end of the novel a sadder, but much wiser Pip, who has definitely learnt a lot through his experiences.