The MA-1 "works" under a relatively narrow set of conditions that I don't see most days. I tried. It is a miserable garment for how and where I live.
I'm not saying synthetic materials are always bad. I own a few jackets in synthetic materials that are good, but I have gone through a lot that are rubbish. For jackets it is more about the technical design than the exact material. I have had lots of expensive jackets that just don't work for my use cases. And a few that do. It is trial and error since I have no idea why some jackets just don't work.
I live in a place where it rains heavily, and in the winter it is often cold, and I spend a lot of time outside being physically active. This means that the challenge is to find jackets that can deal with heavy rain, cold, physical abrasion, and perhaps most important of all: moisture management.
If you spend a lot of time being physically active outside in all kinds of bad weather, you tend to start caring a lot about what materials you wear. Best case for sub-par garments: they start to smell. Worst case: you freeze because your clothes can't manage moisture.
But for what is more or less a glorified sock, at that price I am not buying a piece of plastic. I'd expect more pleasant natural materials.
Synthetic materials vary by many orders of magnitude in quality depending on the purity, molecular weights, antioxidant packages, processing conditions, etc
I haven't tried it so I wouldn't know. But I'll have a look. Thanks for the tip!
As I mentioned, I've gone through a lot of jackets in order to try to find a model that consistently works and it is slightly baffling. I have a long discontinued 20 year old Bergans (https://www.bergans.com/) jacket in a horrific puke green color that works really well, but it is ugly as sin. (It is almost painful to look at :-))
It is one of the few jackets I own that combine good resistance to heavy rain with an ability to vent moisture really well, so it doesn't get clammy. It also traps heat really well so I have worn it in ~ -15C with just two relatively thin merino wool layers. Most of the other jackets I've tried tend to build up condensation when I ride in heavy rain. Which is pretty common weather where I live.
MA-1s are inner lined with a 100% cotton/wool mix. The outer is nylon because synthetic fabrics are generally good for waterproofing (waterproofing is always a trade-off of quality over function) & also just because bombers are generally nylon, but a big part of their construction is using quality non-synthetic fabrics wherever they can to ensure overall quality.
