Don't worry, it's not that old
Ha ha - your partner saying it's a pointless pet - he will probably fall in love with the hamster. My OH didn't want us to get one - but within a few weeks he was worrying about the hamster and within a few months the hamster was sitting between us on the sofa.
Yes I did find the combination of slightly smaller width overall, top entrance and solid sides, made it difficult to fit things in satisfactorily and that was for a dwarf hamster - also he is a very nervy robo and didn't like things coming from the top.
He is still a nervy robo, but actually accepts my hand in the cage now that it comes from the front, gradually, without running and hiding.
But mainly the extra 5cm either side did help set things up as most things go above substrate level.
People used to complain that 80 x 50 cages weren't actually 80 x 50 because the base sloped so much but I think they are quite well designed to be stable at the bottom and give enough space to fit everything in at the top. Unless it's for a tunnelling hamster and then they may need a bigger base. But if they have a good house that's dark inside they don't seem to tunnel as much (in my experience but hamsters do vary).