(BrettM): Gotcha. That makes sense, but the way Septimus goes on about this the only way I can interpret it is that he believes the Dwemer are the ancestors of all the elves because he thinks that only a combination of all their blood can recreate the original Dwemer qualities that are needed to unlock the box. I guess I'm too much "in the game" at that point, and I should know better. I have college training in population genetics -- not that the Bethesda developers have a shred of a chance at having actually thought of it in these terms, of course.
Also bear in mind that Septimus is absolutely bonkers. Genetics also doesn't really play much of a role in a world where you have, quite literally, magic, gods, and spient trees who straight up create you out of a swamp.
IF we assume Septimus knew what he was going on about, i think his practice was more along the lines of; We know all Elves are decended from the Aldmer. There are no Dwemer left, but if you can recreate Aldmeri blood (by combining the like characteristics of the blood of other Mer) you ahve a better chance of mimicing the unique characteristics of Dwemer blood, since you essentially have the source material. Of course, true genetics doesn't quite work that way, but again... magic.
As for the artistic design of Elven armour changing over time, Elven armour is characteristic of Aldmeri style, and thus Altmeri (since the High Elves try to mimic everything the First Elves did). The Altmer are not really given to change, even over unreasonably long periods of time, so theres no reason why the two wouldn't look the same. As far as the Altmer are concerned, it's perfect, and why change perfection.
The REAL question is, where the hell are all the Falmer artifacts the Nords looted, and why is there no Stahlrim?