"This book is sold subject to the condition that it shall not, by way of trade, be lent, resold, hired out, or otherwise disposed of without the publisher's consent in any form of binding or cover other than that in which it is published."

from https://books.google.com/books?id=v-yrLmQNRvsC&pg=PR4 , but there are many other examples.

Many publishers really didn't like used bookstores and libraries making a single book available to many people over time, replacing the covers as necessary due to wear instead of buying new copies of the book.

1) Books go out of print and they don't have anything to sell anymore.

2) A replacement book could cost more than a new cover. I bet libraries would be happy to return the old worn book and get a pristine one, possibly of the same edition, for the cost of fixing the old one.

That doesn't happen, maybe it's even an unprofitable business for publishers, so long live to the First Sale Doctrine.

Right. The language above was an attempt to force libraries to buy a brand new copy anyway, and make reselling used books more difficult. In case it isn't obvious, replacing covers is much more common, and gives excellent results, with hardcovers (look up book rebinding).

Also related is the practice of retailers "stripping" a paperback book of it's cover rather than returning it to the publisher. Publishers would therefore like it to be illegal to buy and sell books without covers, or with replacement covers: https://en.wikipedia.org/wiki/Stripped_book