They are. But it's drowned in the noise about undocumented immigrants, which is a much more emotional issue and more in the consciousness of the general public. If a politician says he wants to improve H1B, he'll get a primary opponent running ads saying he is pro-amnesty. Look at the comments section in any news article about improving H1B loopholes and the discussion is dominated by issues relating to the border with Mexico, amnesty, and undocumented immigrants.