What if all illegal USA immigrants were sent back?

I just saw a rather interesting article on MSN (http://articles.moneycentral.msn.com/CollegeAndFamily/RaiseKids/WhatIfWeThrewOutAllTheIllegalImmigrants.aspx) about what would happen to the USA economy if we sent all our illegal immigrants back home. Here's an excerpt: "Home help (21%): Los Angeles would still have its sunshine, but there'd be far fewer helping hands to clean floors, cook dinner and shush the kids. Not to mention in New York, Chicago, Houston, Phoenix and Miami. Some working parents might have to quit their jobs to care for the kids or break the family piggy bank to attract a housekeeper from a neighbor.

Farming (13%): "Agriculture would come to a screeching halt," says Nicole Rothfleisch, executive director of the Imperial County Farm Bureau in Southern California. She says El Centro, the county seat, has the highest unemployment in the state (18%). But farmers can never find enough local help. Pay is $9 an hour, and the summer temperatures can hit 110 degrees. The locals, she says, "want cushy jobs with air conditioning." Economists say many farmers would go broke as billions of dollars' worth of crops lay unpicked. Farms would merge and switch to crops that can be picked mechanically, like round lettuce or oranges used solely for juice.

Food manufacturing (14%): The big meatpacking and poultry-processing plants would slash production, increase wages (now $12 an hour in Texas) and send managers in helicopters to scour the countryside for workers. In 2006, when six plants of meatpacker Swift & Co. were raided for illegal workers, the company began offering $1,500 bonuses to Burmese refugees in Texas for each friend or relative they could recruit.

Construction (12%): If it looks bad now, imagine an economy where homebuilding is really crushed, says Rick Montelongo, owner of a building and remodeling company in San Antonio. "It would be a huge blow," he says. Workers' wages, which make up 30% of the cost of building a home, would have to rise "substantially," he says. That would make it more expensive to build new homes, resulting in even fewer sales for an industry already experiencing a sharp downturn.

Hotels and restaurants (11%): There'd be a triple whammy here. Latino staff and customers would both be lost, while the price of fresh food would be driven up by shortages. Distraught restaurant owners would pin up job ads at colleges, when they weren't up to their elbows in dish soap. The billions of dollars spent annually by illegal immigrants would disappear, bad news for small restaurateurs and fast-food joints. But over time, the industry would adapt. Self-service cafés would pop up. And more restaurants would serve chicken parmesan prepared in a factory and warmed up in a microwave. Yum.

In light of all this loss within the U.S. economy, why are we so against illegal immigrants around here?