Rigidity of the US Constitution

In Federalist #43, James Madison argues that the Constitution's amendment process is well thought out and good for the country:

It guards equally against that extreme facility, which would render the Constitution too mutable; and that extreme difficulty, which might perpetuate its discovered faults. It, moreover, equally enables the general and the State governments to originate the amendment of errors, as they may be pointed out by the experience on one side, or on the other.

Many other democracies have some process for amending their founding documents, but the United States has some of the toughest restrictions, based on the percentage of votes required for passage.

a. Would it be better if it were easier to change the US Constitution? 

b. Does the difficulty of changing the Constitution make it too rigid?

Edwards, George, and Martin Wattenberg. Government in America 2014 Elections and Updates Edition. 16th ed. New York, NY: Pearson Education, 2015. 55.