I use micrometer-based tools to help with repeatability. In my load data, I specify the setting on the micrometer and then return to that setting the next time I'm making the same load. It's an excellent technique.
Although I don't use micrometer dies, I do use micrometer powder measures. It's a great convenience. The alternative is to use a trial-and-error method, which is always time consuming and can often be difficult to match exactly.
I haven't found enough reason to use a micrometer die because I don't experiment with a lot of different bullets and seating depths. But if I did, I'd seriously consider the micrometer dies.