Just to give one example, BA is fleet constrained and has a number of aircraft types such as 788s which work well on a sector such as EWR, but don't have a First cabin (and there really isn't space). Also First is becoming a smaller cabin anyway, down from 17 seats to 8 seats at the extremes. If First is important then JFK is what you need, you have to prioritise your options between First, daytime and airport. JFK will have First for the foreseeable, EWR may be not. It's a lower cost, higher performance route, First does not pull its weight relative to WTP so EWR is going to be vulnerable here.#

There is a fair chance that EWR will end up Club Suites by then, if that makes a difference. Statistically World Traveller is the safer cabin if I wanted to be obtuse!