"It was/is horrifically wasteful, and could be more profitable for publishers *and* cheaper for readers by cutting out some of that waste--"
Ahhh, we agree again.
Thing is we are paying for that waste. Every time you buy a book your supporting that model.
Cut the waste, cut the price, sell 3 times as many books, make more money.
Everyone ends up happy. Seriously, if you could get a hardcover for just over what your paying for paperback now wouldn't you want that? Assuming author, and book you want to read, etc.
Granted book sellers might not have it quite so easy. They'd actually have to do a better job of anticipating need. But with today's computer world, and inventory tracking software that shouldn't be that big a job.
Order smaller lots, track sales, reorder if it looks like its going to be a big seller.
Every other seller manages to do it, I don't see why they can't do it better with books.