How is the end of Animal Farm ironic considering Old Major's dream for the future and warnings to the animals?

It is ironic considering he speaks of everything the animals want, should have, and never do: ie: not sleeping in a bed. But, by the end of the book the elite pigs are sleeping in a bed with sheets, which is different. Everything that Old Major warned them about and being changed slowly one item at a time throughout the book. Then at the end everything is just as the animals did not originally want it.