Actually I don't get random IDs anymore. I get the same ID every time I join a server. But it's still wrong, it's not my old ID. I hope you can restore the old associations between serial keys and unique IDs or it's going to be a big problem for multiplayer mods with persistent data.
So the problem is that we've been given random IDs that no longer are what they used to be. Not a big deal for most players who only play on Native servers. But for admins and people who play games that rely on your unique ID (like crpg, and a lot of other mods) it's going to mean all of that information they had about our characters is no longer stored to said characters.
So some people's wishes (that I've seen recently) about everyone starting over at gen 0, level 1, may come true.