I respectfully and politely disagree with your statement. It is truly a statement of "Constitutional" language, from the founders and since; language written to help reduce many fears of a Constitutional or "Constitution amending" convention.
As to actual fears and why, I do think the main fear is not because Americans "have never used that tool".
I believe that the fears have been, when considered, that people do not believe that a convention will actually hold itself to:
"The petitioning language used by the states to request a Convention for Proposing Amendments would define the purview of the Convention...and...The Convention would not be allowed to address any subject outside that language."
that a Congress and Supreme Court consisting of majorities not opposed to the extended mandate a convention might try to give itself would intervene simply because that self-extended mandate by the convention was against the rules.
We now, at this moment, have the Democrats in Congress ignoring the Constitution's clear language with regard to representation for the federal jurisdiction of Washington D.C.; acting as if that language either isn't there or can be ignored regardless, and seeking to change the terms of that representation by mere legislation.
What do I need to say about the willingness of a shifting set of 5 of 9 Supreme Court justices to hold themselves, much less anyone else, to the limitations and divisions of powers so clearly laid out in the Constitution.
No my friend, the fear has always been not the design of the founders but whether or not there will be a majority will IN THE PEOPLE to hold such a convention to its Constitutional limits and will that majority be expressed by the existing institutions.
The fear has never been the unknown procedures. The fear has always been will the people have the will to prevent such a Convention from becoming a Pandora's Box, no matter what the rules already say. The fear is that some drive sufficient enough to actually mandate such a convention will be used, by some, and possibly a majority, as a further mandate beyond the protections the founders gave us, and at a time when the institutions that could, by design, block Pandora's box, will refuse to act.
Personally, I prefer individual amendments, one at a time, through the federal and state legislative processes. My own feeling is that if we need a convention, then we need a revolution instead, and yes, I mean one in which we are prepared to fight for what we believe.
Most objections to a Convention for Proposing Amendments tend to lie in the area of a "runaway" convention that goes beyond the mandate given by the states. First I'd like to look at the tools for keeping the Convention within its constitutional bounds as an agent for the states.
So in order for popular whims to turn the Convention into a "runaway" convention that exceeded its legal authority, we'd need all the following safeguards to fail:
That's a lot of safeguards to fail.
That fear for me is not limited to a constitutional convention.
What prevents the House from impeaching the President or Vice President? Evidence? nope, they make the charge and evaluate the evidence. Legal definitions? No, they are not bound by any legal definition, and can define any action to meet the qualification for impeachment.
The ONLY thing that stops an impeachment is the fear of the majority that performing an impeachment might be politically unpopular -- i.e. they might be voted out of office.
If a vast majority of the people are tired of the president, the house can impeach on majority vote and that majority will probably be re-elected for their efforts.
And if in the Senate the opposing party to the president had a large enough majority, or enough of teh president's party was worried about getting re-elected, they could well find guilt by the 2/3rds necesssary.
We could well impeach a President for "not stopping a war when the people were tired of it", even though that obviously is not a "high crime or misdemeanor".
Of course, up until now, the people we elected to office had some concept of a duty higher than themselves to the country, something the democrats lack. I have no doubt that, if they had a 67-member senate caucus, the FIRST order of business would have been a dual impeachment of the President and Vice President.