Interesting, but this does rather pander to the old British Railways mentality that we must have locos of many different sizes as we had during the steam era, and, in your correspondent's humble opinion, this was almost as disastrous an approach as skipping the Pilot Scheme altogether.
I have in my own imagination an outline idea of what British Railways might have been like had the Modernisation Plan and Pilot Scheme been done properly, as I'm sure many others do. In this imagined world British Railways was properly funded and vigorously entrepreneurial and would have produced a much smaller number of standard classes. However, what happened instead was, as we all know, just an extension of the situation that prevailed under steam where they had big engines, little engines, some middle-sized engines that could do most things and some that couldn't, passenger engines and freight engines and shunting engines and some specialised engines for specialised jobs, all coming out from various railway workshops and private contractors who were all following what they considered to be the best practice but often ended up duplicating or overlapping with what others were producing. From an enthusiast's point of view this is great because it creates a rich and varied world, but it is woefully inefficient from an operational perspective. We may bemoan the beigeness of wall-to-wall Cl66s, but this is what an efficient railway looks like.