I'm sorry, but I think that's an incredibly lame Borg origin.
For another: Where's the emotional focus? The sense of tragedy and horror? Your origin of the Borg makes the original species come across as being comically irrational -- "We'll link our brains because it's fun."
Well, seeing as WE are doing it right now; there is already couple out there with implants in their wrists that sends information between the two and signals to the brain about the other's emotional responses - and why, for fun! So, no, I don't find that an all too lame an origin essentially. WE, if we follow what some cybernetics are envisioning, are turning into the Borg. The real tragedy would come to the last person who didn't want the implants to watch what his species - us? - turned into, and its too late to stop - especially if he and others like him who died off were warning everyone of this ultimate gruesome fate.
Imagine if you were that person; and have been screaming and everyone that they're turning into the indiviualless horror that was the Borg we saw on television. And they all keep dismissing you as a fear mongering moron, and you keep seeing less and less individuality between persons, and finally, they turn to you, cold, frighteningly intelligent eyes, and the words, out of a hundred mouths at the same time, "You need to stop. You're screaming is disrupting the harmony of the whole. Resistance is futile."