I think the adherence to Amal stems from the fact that though Concentrics weren't ever fitted the brand, Amals, were. The fact that Mikuni VMs are preferred over Amals I find interesting as I read some time ago that the VMs were based on the Concentric design. They are so closely based that the standard for the numbering system for the jets and the cut away on the slide is the same. I have VMs fitted to my Shadow as getting spares for the original carbs was impossible, or thought to be so, when my father first rebuilt it starting in 1978. Not having much luck with getting the correct fiber washers for the originals, Mikunis were chosen because used Concentrics were the other choice, so why go from one used carb to another when new Mikunis were to be had cheaply enough and spares were readily available. I have to agree though that the quality of Concentrics was at one time questionable at best and on that point Mikunis were the better choice.
Now that spares for the original type Amals are available and are not outlandishly priced I have given serious consideration to swapping back as I have the originals in a box on a shelf.
As for Mikunis looking out of place, I don't think they look any worse or better than any other carb. With regards to their origin, if my father a veteran of 2nd Bn, The Queens's Royal Regiment (West Surrey) and WWII wasn't to bothered about their far east origin, or if he was he never let on, then I don't suppose I will be either.
Steven