A LEGAL immigrant to a country should meet a certain criteria. Make the criteria anything you want, heck even change it every 6 months like the Aussies do, BUT once that criteria is met it should be as smooth and easy as a hop skip and a jump to becoming a citizen, and it shouldn't cost the individual the price of a mid level luxury sedan to go through the process.
Unfortunately in America the naturalization process is just another money making arm of the Government. It also employs a lot of people. The whole process could be streamlined and made very efficient, heck other countries do it for significantly less cost to the individual or free, but they are not going to do it and this in turn causes the ranks of the illegals to swell.
Who in their right mind would want to go through this process? You spend money that would be more useful if you sent it back home, and if the process fails you end up in a deportation center thats basically a jail with people who have committed real crimes. Is it a wonder then that people just "disappear" once they get here?
Illegal immigrants don't feel like they are being unfair because they feel the system is not fair. We let Cubans (and Irish) stay no questions asked, even some with criminal records, WTF because of Castro and lobbyist? But get a Haitian from a few islands over and he gets sent back all expenses paid, so what does the next Haitian or Mexican do when he gets here...disappears. And we're shocked?