Long ago JetBlue points could only total as high as 100, and expired within one calendar year of their accrual. If you held and used a JetBlue AmEx those points never expired.
Now JetBlue points are a much higher denomination, and renew their shelf life one year from each time you fly or gain points. Thus that perk no longer is useful unless you fly JetBlue fewer than one time per year. (Which if that were the case, why would you want their AMEX anyway)
Also the JetBlue business card used to give you 5% back via OPEN savings on flights. This is no longer the case.
The JetBlue AmEx is sadly fairly useless.
It's only perk is on rare occasion they will declare a month or two where flashing your JetBlue Amex will get you a free cocktail once in the sky.
You would likely be much better off with the Starwood Preferred Guest AmEx which can be redeemed on many airlines for a 20% bonus.
(20K points in spending turns into 25K airline miles)