I can't offer a definitive (or first-hand) answer as we were building the first Comet 4s when I joined, but it may simply be that you (and I) are looking at the aeroplane with a "post-period" eye.
What I do know is that once the general shape of the DH106 was determined (i.e. not a rear-engined canard, not a twin-boom and nacelle job and not tailless) not much changed before it flew.