Well, that route is sort of going from Q to Z, when indeed you needed A
to B. Luton is a ways out, and Newark is not the closest to Manhattan.

Actually, Newark airport is closer to midtown than JFK is, and the bus
and train options work fine. La Guardia is even closer but it doesn't
handle international flights other than precleared ones from nearby
Canada.

I think the problem with these airlines is that they're chasing the
market of people who want a better than coach seat on an international
flight, but fly so infrequently that they don't care about the lack of
onwards connections or a frequent flyer program. That doesn't sound
like a very big market.

Also, if you want something better than coach on the relatively short
flights from the UK to the eastern US or Canada, several airlines
have a premium coach that is OK.