I figure that I should explain why I voted like I did.
Alchemy, Mythical minerals... we have that stuff in spades. Every second mod that I install, I have to edit their interpretation of, say, Mithril to work with the 1000 others that I have installed already. All kinds of different mods do it.
But none of them so far have done anything with tinkering and artificting. Which is very unfortunate, because that always seemed way more dwarfy than alchemy. Bells, whistles, knobs and gears. Mechanisms. These are the things that spark the dwarven imagination, not sorcery and potions.
My intentions for metals were, at first, threefold.
1) To bridge the power gap between steel and adamantine
2) To make combat metals of varying strength available in different ways
3) To introduce new options for blunt weapons, including an "endgame" blunt metal.
I feel that I have accomplished these goals with the metals already included. For this reason, I feel that introducing more metals to the same effect would be confusing and counter-productive. There is a point at which variety becomes overbearing, and I'd rather not find out where that point is. The reason this is even included in the poll is to see how others feel about the way I have gone about it.
This leaves two more possible purposes for metals in the current game.
1) Economic metals. Even though these have not been explicitly addressed, the combat metals have provided a number of high-value options for furniture and crafts. White gold is being included as another option for incresing value in v0.11.
2) Metals with unorthodox roles (i.e. alchemy). Like yourself, I feel that this is the most exciting - and, ironically, least explored - possible area of elaboration. Judging from preliminary poll results, I feel like this is a logical next step.
Also, like yourself, I feel that the concept of machinery and tinkering is a theme that should be developed on. Other mods have included metals such as enchanted forms of steel or more complicated or magic-infused alloys for combat. While I acknowledge that some of these mods do an excellent job, I feel that the concept itself is a bit of a cop-out. Enchantment can be used to justify anything, and is only used very sparingly in the vanilla game. I feel that invention, mechanisms, and tinkering are a much more interesting option for expansion.