I think the reason we keep seeing new typeface designs every year is simply because each new design has a different aesthetic feel to it. Type designers look back into type history and combine ideas in new and interesting ways. New typefaces allow designers to create more distinctive work, even if on a very subtle level.

Granted, there have been new typeface releases that are created for specific uses, like reading on small, low-res screens (although this is less important with the rising popularity of high-density displays) . However, most new releases we see are not created specifically for solving new design problems that pop up every year. They are purely aesthetic in nature.

Jeremiah Shoaf.