A 4 engine line up for a model range that sells around 600 units per annum is surely a non starter.
I see your point and it has to be said that whilst the 2.0 litre engine is more or less traditional for the +4 there have been variations up and down. However, given how quickly the +4 SS sold out, even though it is only made in RHD, there is clearly a demand for a 200 hp trad Morgan. Also perhaps one can say that already Morgan is able to produce limited runs of cars with special engines and sell them within, or perhaps in addition to, the 600 units a year.
I, for one, would have ordered one as quick as a flash if I could have had it with the options I want, and I suspect I am not alone. In fact if Morgan told me I could have that engine I would change my order tomorrow. It is not that I can not find the extra to pay for a Roadster 3.7, it is more that I don't really want a 260 hp car and I don't want to pay the extra taxes and insurance either.
One way or the other the future will bring some engine changes. It will be interesting to see what Morgan decides.