As Bitcoins are the first cryptocurrency to use block generation and so forth, one can assume 10 minutes was a arbitrarily chosen. Any value that was big enough to propagate the new block through the network before another miner would be probable to generate a new block would be good. On the other end blocks shouldn't be too scarce, as it would take too long to get confirmations. An hour of computation is considered safe from being tampered with, so dividing that time into neat parts can give you 10 minutes.
There probably isn't any discussion available on this topic, as the first Bitcoin version was created by Satoshi alone, so until he reveals his true identity or comes back to the community, the exact reasons can't be figured out for sure.
