Lowering the threshold for amendments would actually weaken the Constitution, not make it stronger.

Imagine if they just kept flip-flopping back and forth on abortion or citizenship status every 8 years, at a Constitutional level. Every federal rule and regulation that Congress tried to implement based on current law, would have to be renegotiated every time an amendment was altered. The federal government would be locked into a permanent state of revisement, and literally nothing else would get done, as long as those basic issues remained permanently unsettled. Not to mention, people’s lives would be constantly fluctuating between opposing statuses.

The harder it is to make amendments to the law, the more stable the society becomes. Once something is codified into the Constitution, it should be extremely difficult to reverse. 2/3rds is actually a very reasonable majority under the circumstances. Less would be too easy…and more would be virtually unachievable.