If a logo needs a 300 word explanation, it's probably not doing its job very well. After all, when it's out in the big wide world no one else will ever get that explanation when they see it.
But I've found giving some rationale as to how you came the solution is important for the client to get a bit of context and to avoid the questions that get answered with 'yeah we know, we tried that' - trust us, it won't work.