They're not designed to break, they're simply picking the trade-off point that tends towards the "lightweight enough to wear all day" end of the continuum.

I don't believe it. I have this pair of safety glasses I bought from the hardware store for $5 and they are super light weight and rock solid. I could wear them all day and not even notice. Sometimes I even forget I am wearing them and wear them around inside for a while when I'm finished my work.

If they had some tint and UV protection and I would consider using them as shades.

update: I talked myself in looking at the hardware store website and my next sunglasses will be be some 3M safety glasses with a dark tint and uv. And less than $20.

Those aren't prescription glasses are they?

I'm really surprised I haven't heard this more often, because it seems like a given. AR glasses should be trying to offload as much work as they can to the supercomputers we carry around in our pockets. They have a much larger form factor that can support more compute, more battery, a better antenna, etc.

edit To be clear, I don't think we're anywhere near having cheap AR glasses that can just delegate all the work - rather I think there's so much compute that's necessary, we need the combination of what we can fit onboard the glasses and in our phones to make a compelling product.