Q61. "How we can account for the fact that the U.S. Constitution has been amended only 27 times in the past 200 years? Do you have any feed back on this?"
A. Actually, since it was written in 1787, it is the last 223 years, as of 2010...
The beauty of the Constitution is its brevity. It does not attempt to mandate too much, like some constitutions which are hundreds of pages long. Any power it does not grant the federal government, and which is not otherwise expressly forbidden, is left to the states. Think about how much you don't have to write down if you say "these are the rules, and anything not in the rules is OK."
If you look at the amendments, aside from the Bill of Rights, you'll find that most are there to fix errors, clarify, or extend voting rights in one way or another. Very little has actually changed (aside from the landmark 14th).