I think John is sort of right, we all have our favourites/obsessions and assume everyone else agrees. Unfortunately if you are producing kits that fill your own interests, you are probably doomed from the start.
Whatever Simon believes the G1 norm should be, he will know a large majority of G1MRA members and the "unattached" G1 brigade, plod along in the old way with 10mm - it does make you compatible with the majority of garden lines, test tracks and layouts.
Some kit manufacturers who produce kits to earn a living (I think there are a few) aren't going to spend on tooling, patterns, and all the other overheads to produce a kit just because a few say they will buy, he's going to pick something reasonably popular that will appeal to people with money in their pocket - how about a small Prairie in 1/32 - I bet that would sell a sensible amount, small, green and a very recognisable shape.
But a Ruston 48ds, Manning Wardle and a class 14 are all a bit unusual in most peoples plans for their railway empire unless you have an interest in industrials, light railways or steelworks.
When I started a thread regarding G1 North which was a public exhibition, promoted by a group of G1MRA members in the "north" and backed by G1MRA, with a good selection of G1 traders - with supplies of both 10mm & 1/32 hardware on offer, the only response was strangely from a few with a G3 interest.
So where was the upsurge in 1/32 interest then ? - finescale or otherwise.