Why no impeachment
When a president repeatedly violates the Constitution (like unilaterally making changes to laws), the remedy under the Constitution is impeachment.
I recently heard a constitutional expert, when asked if all of Obama's violations of the Constitution warranted impeachment, reply by asking what the questioner meant by “all,” and how about any one of them?
Imagine if any other president had committed just one of these violations. Does anyone believe he would have been allowed to remain in office? Richard Nixon, anyone?
So why hasn't Congress taken any action? Because, generally speaking, we have garbage representing us. Those whose duty is to uphold the Constitution are more concerned with preserving their little fiefdoms.
And how did this come to be? Because, for too long, too many people have been apathetic and therefore have not held their elected representatives accountable.
And they don't seem to realize that the fruit of apathy is tyranny.