With regards to martial arts progress, well, now we indeed have somewhat better understanding of body mechanics, so this kind of progress helps to develop methods of striking faster and harder.
From another perspective, all the way back there always were tremendously effective martial artists, effectiveness of which was mainly explained using different knowledge and terms base, now often referred as "esoteric". Well, regardless of what explanation existed at that moment, the effectiveness was there. Which means the modern "mechanical analysis" approach isn't necessarily represents any real progress of martial art in comparison to the past, but rather makes some aspects easier to grasp for practitioners.
Another note… There is a natural contradiction between desire for ultimate effectiveness and mastering of a specific martial art. Any art, including martial, teach you how to achieve the desired result in some particular way, that is, limiting your choice just to the tools declared as a part of that art. Brush painting still exists while so much more effective imaging technologies are widely available, and practitioners of this art do limit themselves to a brush. If this or that particular art doesn't have a roundhouse kick in its toolbox, you are expected not to use it as long as you consider yourself inside of that art's framework; even though roundhouse might be the best way to handle some specific situation. Well, in a real fight nothing limits you, but here you cross the line between martial art domain with its natural borders and a domain of self defense with its sole rule "use everything you know".
Ultimate martial effectiveness presumes no limitations in the way you respond to the situation, and thus no martial art can be ultimately martially effective. Martial artist can, though it rarely happens if he limits himself to one art.
Speaking about Aikido, we speak about art, not an artist. It is the artist who should adopt himself to modern speed, and make himself to be able to deal with BJJ, or a MMA, or Krav Maga, or even hand grenades; not an art.
Aikido is a beautiful martial art, existing, as any other art, within its own domain. Its techniques may evolve, but to stay Aikido, it has to stay in its domain.
Martial artist practicing Aikido can develop himself to any level of martial effectiveness, however when teaching, he must always realize where is the border between Aikido and his own extensions developed for sake of martial effectiveness…
This is just where I'm at this moment...