The visual quality may be lousy, but it's relatively comfortable. It really doesn't matter how good the screens in it are, or how much dumb "tech" it is full of, if it's just generally not comfortable to wear.
Being 500 grams with most of that in the front (for that stupid glass and "face" thing), it's not going to be a good time. Without a back to front strap, it's not going to be comfortable, and the "solution" for the weight of just clinching it tighter against your face is the WORST solution (believe me I've tried) and only results in more discomfort.
I don't know how lightweight you have to get before something is comfortable to wear on your face for extended periods, but it is probably closer to 250 grams than 500
Welders wear face shields that are more than 500 g for very long periods. I have no doubt that Apple will be able to figure something out.
At this point though, all of this is speculation. I expect v1 to suck, v2 to be a little bit better, and v3 to be the one that gets it right. I'm guessing that's about 5 years out.
The launch unit probably should be a heavy mess and if it isn't, maybe they weren't ambitious enough.
Welder's face shields do not have the "gasket" pressing against your face, they are closer to a hat, with the way they distribute the load onto your head and how they otherwise do not touch you.
There are all kinds of attachments you can get that can bring the mass into that 500g neighborhood. The ones from the previous generation were easily 500g.