Shetlands, the stocky little pony are cute ! The Registered shetlands look like small horses.
And Minis are just pets , and many of them are malformed, short legs big heads .. dwarfish in appearance . I used to ride and drive a shetland when I was around 12-14 , he was not mishappen. I forget how tall he was , but he was not super tiny.
That cross is a bit different, though. Both horses involved there are breeds that are very commonly bred for riding. Minis are not, so it's not likely that the result would be a nice quality pony like the one that you previously had experience with.
Miniature Horses are not just ugly malformed short legged useless pets. And many, many of them are from
Shetland blood. A lot of them are duel registered as AMHR/ASPC (Miniature/Shetland) I'm not sure how crossing a 41" tall Shetland to a Thoroughbred makes the world of difference vrs. Crossing a 37" Miniature to a Thoroughbred? Neither seems like a bright idea to me and if one is OK and regularly produces nice ponies then I am sure the other would as well.
Stevenson - a properly bred Miniature Horse looks just as much like a small horse as a properly bred Shetland will. Well built is well built. Any Miniature with stubby legs, roach back, short neck and a large head is a dwarf - not stock that should be produced from obviously and not something that should be used to lump all Minis into the same group.
My stallion is 31" tall and 1/4 Shetland. He can pull two adults down a trail, should have been shown jumping and isn't bad on the eyes.
I'm not saying that its right, assuming the nature of the post I'd guess that it wasn't two "quality" animals that were bred either. To me, that is the biggest issue. Just correcting some assumptions is all.