But why would we want that outcome? The Borg are universally despised on ST by all other sentient races, and assimilation is resisted whenever possible.
It's the same as arguing that the replicators on Stargate SG1 should be the logical outcome. Technologically, they are superior, but they're not a preferred outcome. Similarly, one could argue that gray goo or Carpenter's creature from The Thing are superior, but we don't want a world of gray goo or things.
I argue because it's the logical progression of our species and continues the trajectory of our highest ideal: understanding the universe.
We can't do it with our biology, limits to understanding, reasoning and perception, so something that is not biologically restricted needs to be our successor.
It's the same as arguing that the replicators on Stargate SG1 should be the logical outcome. Technologically, they are superior, but they're not a preferred outcome. Similarly, one could argue that gray goo or Carpenter's creature from The Thing are superior, but we don't want a world of gray goo or things.