Like you, Octopus wanted me to replace mine with a Smart Meter, as mine was ‘coming to the end of its life’. Apparently they can not order the old style meter for replacements. After repeated requests to be put in touch with a line manager they gave up.
Nothing against Octopus, here. Found them to be fair and straight forward.
Yes, there is a legal obligation on energy companies to meet targets for smart meter installations. They cannot install any new non-smart meters, and are encouraged by these targets to replace existing meters.
The government target is for smart meters in all households by the end of 2025.
Ours was two smart meters (one for electricity oe for gas) when we moved in, and since we had solar installed, we switched to Octopus, and are on their half-hourly variable tariffs for both import and export.
At this time of year, we are getting paid a lot more than we are being charged. And then November to February, we charge the battery overnight, between 2:30 and 5:00, which usually provides all the electricity we need, at the cheapest rates. We couldn't do any of that without a smart meter.