Because no one really needs it.
Did you read the comment section? Even @edicted needs it.
Java is the 2nd most popular programming language in the world. Saying that people don't need it is an erroneous statement.
This new API could easily cause an influx of new developers/users on Hive. Something like that happening might even send the price of HIVE to the moon.
RE: HIVE JUMP PROPOSAL - JAVA API FOR HIVE