The TLC document suggests the last fare increase to JFK was in September 2012, which is a bit over 10 years ago (not sure why media saying "almost 10 years").
That's an average annual increase of 2.9%. For reference, the overall CPI between 9/12 and 11/22 (latest available until tomorrow I think) increased at an compound average annual rate of 2.5%. In the NYC area the CPI only grew at a +1.5% annual rate (surprisingly).

Apparently the original plan was for a $65 flat rate, but after public comment (presumably from the drivers, not the public passengers!) they raised it to $70. At $65 it would have been a 2.2% annual increase (below overall inflation).

I do agree more frequent increases make more sense, although presumably it's quite an effort to get something like this done (as well as MTA fares).