Just my two cents: the more grey you have, here and there, the harder it is to cover even at the hairdresser. Especially at the temples. It's easier to dye it when there is just a bit and keep up with it than to let more and more of it grow out and have to cover a bit in your roots, a bit at the temple etc. I supposed the alternative is to let it all go gray, change your mind and then cover the whole head at once.
I find although it's great that some people own it, yay for them, it's not very attractive to see gray hairs, which are a completely different texture, here and there in the otherwise beautiful head of hair.
I do not intend to go completely gray until I am at least 80yo.