I have a bit over half an acre, plus some reserve land, and I mow a bit at the neighbours and a bit up the roadside. A bit over an acre I mow in total. I'm thinking about going up from a BX to a B. I had a discussion with the better half about moving to a larger property, and finally she suggested I can just have the tractor I want on the property we have - moving house is way more expensive than just buying the tractor.
It's good that you recognise you don't need it, you want it. And so you should buy the tractor that makes you happy - there's nothing worse than spending a chunk of money and secretly wishing you'd spent that last $1,500 that really would have made you happy.
I would agree with others though and focus on attachments a bit more than HP. A 23HP is plenty, the BX23s with backhoe is built on the 23HP platform, so Kubota themselves think that's plenty of power in the tractor.
Attachments are what make the tractor useful, get a loader (if you weren't already), mower, chipper, rear blade (or front blade for snow), weight box, some chain hooks and chains, get the SSQA on the loader and some forks.