Probably because "latino" is a made up word. The latin language comes from ancient Italy, and we are not being invaded by a bunch of guys dressed like Roman gladiators. I asked a hispanic guy once why they were called latino and he said it is because the spanish language has latin roots. The problem is, so does english, french, italian, and so on. He said he didn't like the word hispanic because it sounded too much like "spic" to him.
"....he didn't like the word hispanic because it sounded too much like "spic" to him."
Sounds like "hiss-panic" to me.