If it’s just for reading books, it’s still not really a problem in the vast majority of cases(aside from things like made up words where you’d need to somewhat know the kanji to guess what they mean and books that actually talk about some individual kanji at some point, but I don’t think either of those is particularly common, and if it’s the latter you’d probably get an explanation anyway), since books use words and not individual Kanji. I won’t say anything definite about other stuff since reading fiction is what I have the most experience with, but I personally have a hard time seeing it being more important for speaking or listening than for reading. (For writing, I don’t know how useful or not it’d be to know the individual kanji well)
That said, not knowing the individual kanji well does mean that you get more reviews on wanikani, and sometimes you can guess what words mean without having to look them up if you know the kanji(which you probably already know, but still), so it’s not like it’s entirely useless to know them either. I also personally find that I have an easier time telling similar-looking words apart if I know the kanji well. I have no idea how to go about learning them better if you want to do that though, because it’s not something I’ve put a lot of effort into(since it hasn’t been necessary for what I want to do at the moment).
All of this is just based on my experiences though, and it’s not like I’m an expert or anything