My Avatar is a Dalek, therefor your argument is... EXTERMINATED!!!
You know who can tell me something I already know? Me. All the time. I'm really good at telling me stuff I already know. I don't need help in that department. I don't know about others, but I can't imagine I'm alone here.
The Meaning of Life, the Universe, and Everything.
Personally, I don't think 1 new ore type is a significant change to minecraft; it simply contributes to power creep. It certainly is an interesting idea, and I would definitely try a mod about this out.
On the other hand, more end game content is definitely warranted. Minecraft has been out long enough that it's time for an "expansion pack", so to speak. Add twilight forest, or something like "Better Dungeons" mod. I understand that these mods could be the answer to what I'm asking for, but I really feel like the core vanilla experience has become lackluster without more "adventurey" style content.