Ignoring all the other benefits of HTTPS, it means you can securely transfer the password itself to the server, or a deterministic hash of the password which the server hashes again. Not to mention that you can use a stronger hashing algorithm, like bcrypt. There might be other ways to do this, but https is definitely the most practical.
who cares if you need a rainbow table?
If the passwords are moderately strong and you are using a good hashing algorithm (that is salted), then creating a big enough rainbow table (or brute forcing) is intractable.
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Ignoring all the other benefits of HTTPS, it means you can securely transfer the password itself to the server, or a deterministic hash of the password which the server hashes again. Not to mention that you can use a stronger hashing algorithm, like bcrypt. There might be other ways to do this, but https is definitely the most practical.
If the passwords are moderately strong and you are using a good hashing algorithm (that is salted), then creating a big enough rainbow table (or brute forcing) is intractable.