But in fact, if you check out Obama administration policies, it appears that one can indeed simply decide not to follow the laws one disfavors:
Don't like the War Powers Act (all that pesky consultation with Congress)? Ignore it.
Unhappy about the existence of the debt ceiling? Ignore it.
Don't like the Commerce Clause's limitation on government's ability to regulate citizen choices when it comes to health care? Litigate it.
On a more serious note, each instance of the Obama administration's deciding to ignore the law puts more stress on our constitutional system of government. Each of the instances noted above is an ugly, needlessly dramatic way of trying to reach policy objectives that are, in fact, unpopular. And that, over time, undermines the legitimacy of government, and makes it appear (and become) ever more lawless.
Good presidents just don't do this. For example, there have been many reputable scholars who legitimately have differences of opinions about the constitutionality of the War Powers Act. Even so, President George W. Bush went to Congress, for example, before committing troops to Iraq -- because it's unwise to provoke constitutional crises.
It's just part of being a good steward of the country.