Some months back a caller asked me what I thought was the "worst" Constitutional Amendment. He postulated that it was the 17th, which moved the election of US Senators from the State Legislature to the popular vote of a given State.
Look, from a purely strict constructionist viewpoint - which by the by - NOBODY holds - every amendment from the progressive era has been "devastating." Some more than others, but all of them destructive to the original ideas of a strictly separated Federal and State system.
That said, I have always believed that the 16th Amendment was the really destructive amendment. NOT because it established an income tax. What most people do not understand is that an income tax was always on the table. What the 16th Amendment did was remove the most effective deterrent to the income tax.... apportionment... and with the tearing down of that barrier, the door was opened for the Federal Government to subsume the States with, you guessed it, money...