While I certainly am not happy with the efforts of ultra conservative Republicans to shut down the federal government over their opposition to Obamacare, unlike a lot of people, I don't see anything wrong with their many votes to repeal it. Just because a bill is passed and becomes law doesn't mean that those opposed to the legislation should throw up their hands and move on to other concerns. If you believe that the direction the country is headed is wrong, you SHOULD continue to fight to steer it in the direction that you believe is better.
Let's say that a Tea Party candidate wins the presidency in some future year AND this group garners enough seats in Congress to set their agenda. If they then passed legislation that mandated that every person must own a gun OR they mandated that fundamentalist Christianity was enshrined as the national religion, I would HOPE that more progressive-minded members of Congress would try to repeal it at every opportunity. They might offer up legislation 50 times and lose all 50 votes. But I would hope that they wouldn't simply throw in the towel, shrug their shoulders and say, "Gosh, it's the law of the land now and so why fight it?"