Ouranos was not just any old god. He was—as his name makes clear—the total embodiment of the sky, ouranos the noun is what you see when you look up at the sky quite literally. It makes sense then that with Gaia (gaia means earth) many beings would come forth.
Also, take a look at what exactly is being produced. Hesiod says that the blood created the Seasons, Erinyes, and the Giants, but not Aphrodite, who instead was created when his testicles fell into the sea. That's just Hesiod playing with names, since the Greek word for sea foam was aphros. The seasons, on the other hand, are naturally created in combination with powers of the sky (or so it would seem to pre-science man) and the earth.
The Erinyes' play a role in "avenging the natural order"1, which included tormenting those who commit parricide (i.e. killing your father). It makes then to locate their origin in the very first act of a son cutting down a father.
Also, it should be noted well that Ouranos is not dead. Ouranos is an immortal, and no Greek god can die.
Finally, there are parallels in other traditions. One that comes to mind is the body of Kagutsuchi, who came out of his mother in a ball of fire, burning her to death. As punishment, the kami (Japanese gods) cut up his body into eight pieces:
which became eight volcanoes. The blood that dripped off Izanagi's sword created a number of deities, including the sea god Watatsumi and rain god Kuraokami.