Using the CPI Inflation Calculator (https://data.bls.gov/cgi-bin/cpicalc.pl), here are the values of $100 through all of the key Jeopardy! dates:1964 - $100.00...2016 - $774.22
So everything on the board today is 20 times what it was in 1964, yet the dollar itself is only worth a little less than eight times as much.Tells me everything I need to know, I think.
I think "only the winner keeps his cash" dilutes that a bit, but your position is otherwise well-taken.
Personally, what I'd rather see is a return to the former style of play that didn't emphasize getting every clue revealed in a half hour, where there could be upwards of five or more clues untouched by the end of a round.