Actually it is necessary. If you have a rationale it should be shared unless there are good reasons otherwise. It's more likely to get buy-in to what may well be an otherwise incomprehensible idea or at the very least assures everyone that you aren't actually deficient of marbles. It ensures that new situations can be dealt with appropriately. It enables the process to be modified or dumped if circumstances change to make it inappropriate. At the very least it makes you check that your rationale was well enough thought through to enable you to put together a coherent explanation.
It also allows you to draw intelligent input from the people who will have to execute your wonderful idea, and who may have the required expertise to spot issues, or even enhance the proposed concept (let's not forget that). The challenge, is, of course, that that requires leadership instead of management (there's a large difference between the two).