If only people bought high-end stuff... often enough, they buy low-end stuff, blocking off a product category for a while - e.g., you're not going to buy a proper quality coffee maker for yourself if you just got a shitty one as a gift from a relative, because you'll worry about offending that relative.
Asian cultures just give money, well AFAIK.
In Poland money is 100% acceptable too. We had a wedding couple years ago, just said on the invitation that we're saving for the honeymoon, all guests just gave money, no other gifts.
I'm not the biggest fan of Amazon, but one thing they do well is gift receipts that let you return the gift for Amazon credit without letting the gift sender know you didn't like their gift.
Indeed, especially because you're not supposed to get them stuff that's actually useful, like a decent oscilloscope or a proper set of cone wrenches.
We used a Google spreadsheet for our gift registry ten years ago. One of my friends, a sheet metal worker, gave us a really decent toolbox. Still using it.