If Morgan updated the trad, it would probably be similar to the Plus4+, or the MGA. Any more modern would probably be too much. The thing is, if you could have a Plus 4 styled as now, or an enclosed body plus 4 with flowing wings, which would you go for? For me, the shape is what its all about.
You are erecting a straw man. Morgan tried the MGA type style back in my yoof and it was a failure.
But the styling can be updated taking a cue from the likes of Mini who have maintained a very similar shape but in a more modern style.
For those that hanker after the trad trad, you could always take the present trad and put ( say) an old Ford 4 pot in it, say something from the 50s. Non synchro gearbox and that would keep the purity of the old car experience.